Add Breeze theme

[codebrainz]

A new theme inspired by KDE Breeze theme.

Submitted by direct email:

https://gist.github.com/codebrainz/94df8babb4e4f3493efa39f8208cefba

[codebrainz]

This is quite nice, but the indent_guide and whitespace colours are a bit too dark, IMO.