Fixed: Download Svg Button

Merge pull request #195 from DanielHabenicht:download

element.getCTM() returns `null` if one of the transformation matrices
is zero. This fix uses get_transform_matrix instead.

Co-authored-by: sents <finn@krein.moe>

* use join
* don't use arrow functions

Bump ws from 7.4.5 to 7.4.6

Bumps [ws](https://github.com/websockets/ws) from 7.4.5 to 7.4.6.
- [Release notes](https://github.com/websockets/ws/releases)
- [Commits](https://github.com/websockets/ws/compare/7.4.5...7.4.6)

Signed-off-by: dependabot[bot] <support@github.com>

Co-authored-by: sents <finn@krein.moe>

add board name for downloaded file

Replace mover tool by selector tool

Make navigating overflowing menu more accessible

(and add type annotations)

Bump handlebars from 4.7.6 to 4.7.7

Bumps [handlebars](https://github.com/wycats/handlebars.js) from 4.7.6 to 4.7.7.
- [Release notes](https://github.com/wycats/handlebars.js/releases)
- [Changelog](https://github.com/handlebars-lang/handlebars.js/blob/master/release-notes.md)
- [Commits](https://github.com/wycats/handlebars.js/compare/v4.7.6...v4.7.7)

Signed-off-by: dependabot[bot] <support@github.com>

Update dockerfile COPY to use node user

Fix: Spelling of a comment in server/check_output_directory.js

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