Add syntax coloring from `highlighting-kate` (used by PanDoc)

PanDoc (plugin [pandoc_reader](https://github.com/liob/pandoc_reader)) seems to be using `highlighting-kate` for syntax coloring, even with the `pygments` option. Consequently coloring in this theme does not work (everything is inside `.sourceCode` instead of `.highlight` and quite some things have been renamed -- eg. comments `.co` instead of `.c`).

I copied the styles from `highlighting-kate`: https://github.com/jgm/highlighting-kate/tree/master/css