wbo is now more observable

WBO does not work with node 8

Fixes https://github.com/lovasoa/whitebophir/issues/164

See #153

Fixes #100

* Allow parentheses in board names

* Pass over the string only once while escaping html special chars (#82)

Co-authored-by: Paolo Bolzoni <paolo@cagla.jp>

* Add a spanish translation

Thanks to @beccobunsen

See #94

* add an italian translation

Improve the spanish translation and

* Added "free online whiteboard" to the main title

* add translations for grid

* Fix translations for "white-out" in es and it

Co-authored-by: Paolo Bolzoni <paolo.bolzoni1@studenti.unipr.it>
Co-authored-by: Paolo Bolzoni <paolo@cagla.jp>

* make live version render single-point paths the same as preview does

* implemented smoothing in server side rendering

* separate preview from export

* ensure correct handling of paths with only one child

* break out rendering of 3rd point and up into separate function

* changed test for 2 points to math current implementation and added a test for a bezier curve with 3 lines

* deduplicate code to extrapolate points for bezier curves

* fix merge

* Factor more code between the client and the server

Completely remove the straight line approximation foor paths

Vastly improve preview performance

* Add support for opacity in preview

* Stream board previews to the browser

Previously, svg board previews were generated in memory
and then pushed to the client.

They are now streamed to the client without blocking the main thread.

# Performance

## Before

$ ab -n 30 -c 15 http://localhost:8080/preview/ic3
This is ApacheBench, Version 2.3 <$Revision: 1843412 $>
Copyright 1996 Adam Twiss, Zeus Technology Ltd, http://www.zeustech.net/
Licensed to The Apache Software Foundation, http://www.apache.org/

Benchmarking localhost (be patient).....done

Server Software:
Server Hostname:        localhost
Server Port:            8080

Document Path:          /preview/ic3
Document Length:        14352691 bytes

Concurrency Level:      15
Time taken for tests:   19.499 seconds
Complete requests:      30
Failed requests:        0
Total transferred:      430588920 bytes
HTML transferred:       430580730 bytes
Requests per second:    1.54 [#/sec] (mean)
Time per request:       9749.374 [ms] (mean)
Time per request:       649.958 [ms] (mean, across all concurrent requests)
Transfer rate:          21565.33 [Kbytes/sec] received

Connection Times (ms)
              min  mean[+/-sd] median   max
Connect:        0    0   0.1      0       0
Processing:   727 8885 1561.6   9220    9817
Waiting:      718 5380 2668.8   5569    9549
Total:        727 8885 1561.6   9220    9817

Percentage of the requests served within a certain time (ms)
  50%   9220
  66%   9239
  75%   9245
  80%   9248
  90%   9560
  95%   9811
  98%   9817
  99%   9817
 100%   9817 (longest request)

## After

$ ab -n 30 -c 15 http://localhost:8080/preview/ic3
This is ApacheBench, Version 2.3 <$Revision: 1843412 $>
Copyright 1996 Adam Twiss, Zeus Technology Ltd, http://www.zeustech.net/
Licensed to The Apache Software Foundation, http://www.apache.org/

Benchmarking localhost (be patient).....done

Server Software:
Server Hostname:        localhost
Server Port:            8080

Document Path:          /preview/ic3
Document Length:        14352687 bytes

Concurrency Level:      15
Time taken for tests:   17.647 seconds
Complete requests:      30
Failed requests:        0
Total transferred:      430588020 bytes
HTML transferred:       430580610 bytes
Requests per second:    1.70 [#/sec] (mean)
Time per request:       8823.254 [ms] (mean)
Time per request:       588.217 [ms] (mean, across all concurrent requests)
Transfer rate:          23828.86 [Kbytes/sec] received

Connection Times (ms)
              min  mean[+/-sd] median   max
Connect:        0    0   0.1      0       0
Processing:   719 8212 1440.6   8657    8810
Waiting:      701 4666 2324.8   4788    8769
Total:        719 8212 1440.6   8657    8811

Percentage of the requests served within a certain time (ms)
  50%   8657
  66%   8670
  75%   8691
  80%   8790
  90%   8802
  95%   8808
  98%   8811
  99%   8811
 100%   8811 (longest request)

* Write the element id and opacity only when needed

* Fix a bug in wbo_pencil_point

* Rework the integration tests for the pencil tool

* Test server-side rendering in integration tests

* Remove unused function

* Remove unused id fallback

* set return types

* fix rectangle

* set fill for rect in stylesheet instead

Co-authored-by: Ophir LOJKINE <pere.jobs@gmail.com>

  - use promises instead of callbacks
  - avoid polluting stderr, and instead log rendering time in the standard log format
 - cache rendered boards for only 30 seconds

* remove extra urlencode call

* asser that board name only contains allowed characters

* Log the invalid board name on error

Co-authored-by: Ophir LOJKINE <pere.jobs@gmail.com>

* include promise polyfill

* remove es6

* add viewBox to every icon

* change self closing to explicitly closing tags

* replace window.scroll.. with document.documentElement.scroll..

* verify document.activeElement.blur() is a function before calling

* fix visuals of color chooser (colorpicker still sometimes buggy)

* do not attach to mouseleave event in IE

* attempt removal with usecapture true in IE as well, this fixes the tool switching issue

* fix text tool for IE

* fix cursor for IE

* change curMode to boolean and rename to 'active'

* replace minified canvascolor with unminified code

* replace if else structure with switch statement

* compile polyfill for each browser individually

* remove static polyfills from board.js

* Fix broken js reference

* Fix unused variable and empty console log

* Allow serving non-minified polyfills for easier debugging

* Add proper caching for polyfill.js

This request is on the critical path, we should try to make it fast

* Include more polyfills

All the DOM polyfills were missing

* Update dependencies

* Add missing polyfill

Our custom polyfill was deleted, but the one from polyfill-library hadn't been added

* Remove feature detection for Node.contains

We now have the function in the polyfills

* Update polyfill caching logic

* Remove content-Length header

Co-authored-by: @lovasoa

* change url to hide app behind a relative path

* pass some of ther server configuration through to the client

* serve static files and connect to socket.io correctly when a URL Prefix is set

* Revert the changes to opengraph meta tags

opengraph meta tags need to be absolute URLs

* Remove unused commented-out code

* fix background.png url

* use prefix path for open graph metadata

* Revert changes using server side url modifications

* get open graph and socket.io url from request url / window.location

* remove debug console.log

* Fix favicon when not running under "/"

* Add proxying instructions to the README

Co-authored-by: Laurent Mazet <mazet@softndesign.org>
Co-authored-by: ophir <pere.jobs@gmail.com>

The behavior of `Date.parse` is implementation-dependent and hence
cannot be relied on for security purposes. In particular, the
implementation in Node.js does accept strings such as
`../../../etc/foobar-0` as valid (thanks to the trailing digit).

The failure to properly validate the filename is not exploitable, as
slashes will never be contained in `parts[2]` thanks to the foregoing
`split`, but it is probably still better to have a proper validation in
place.

There are now several different configuration
variables through which WBO can be configured.

Thanks @iblech

Fixes #34

See 63db84f7dd (commitcomment-38508311)

Switch from the unmaintained node-static to serve-static.