Style markup headings the same as constants.
Style tag names and attributes differently.
Remove unused keys/values.
Merge branch 'variant'
Remove empty style/setting blocks
Add selection border and inactive selection colors.
Highlight variable.parameter (same as lang/other variables)
Change the color of markup tags.

Courtesy of FichteFoll. Blame him.
Update diff colors.

Courtesy of FichteFoll. Blame him.

- Give add/delete foreground colors.
- Add a generic markup.changed
Lighten the background of embedded sourcecode.

Courtesy of FichteFoll. Blame him.
Temporarily fix ST3 update's sidebar stuff.

Because now we have two disclosure indicators. This is confusing. Why?
Fix icons / panel ghosting.

Not 100% sure, but looks like it had to do with icon/text field/etc.
sizes or something.

All old find bar icons have been replaced with those from Freesia.

Closes #24.
merged from upstream