Release version 0.8.0

Update changelog

Update changelog

Update appveyor token

Bumpy copyright year

Update changelog path in nsi

Adjust completion colors to have better contrast

These are darker and have at least 4.5:1 contrast, which is the WCAG AA
target for normal text.

Bump copyright year

Use wxButton for lua bitmap buttons

wxButton allows bitmaps since wx 2.9, and wxStaticBitmap doesn't seem to
capture mouse events on mac.

Make deployed releases drafts