David Winterbottom
3931d3b1cf
Extend offers to work when taxes aren't known
This involves some quite involved changes to the internals of how offers
and organised. A new boolean field has been added to the offer model to
indicate whether to apply to prices exclusive of tax. This is used
within the offer methods to determine whether a basket meets a
condition, and how to apply the benefit if it does.
Fixes #925
Fixes #924