Merge pull request #1 from will1b/patch-1

Fix dark background of search stream items
Merge pull request #2 from will1b/master

Allowed custom column header heights
added new column headers (light version)
removed commonly used line
added new column headers (dark version)
added hover colours for timelines (light version)
added empty file for dark hover colours
revert some changes
removed tweet-hover-* files and merged them
added missing column-type-mention coloring
removed import for tweet-hover-*
Merge pull request #2 from pixeldesu/master

Update