Using the picker with syntax highlighting the
fallback `ui.selection` makes a lot of text,
especially for the light variant, hard to read.
Instead, use a lighter background for highlights
* theme: add papercolor light
* fix typo
* add markup highlighting
* theme: added diff colors
forgot to add it to PaperColor Light
* fix some ui colors
* assign more color for markup headings
* change heading color to bright7
