Edited vim colors to work with termguicolors on truecolor terminals

[sprockmonty]

set termguicolors now works and can be left on Specifically to fix issue #3 and issue #7

[h0rv]

Can this be merged?

[Nate-Wilkins]

I've switched to using this and it seems to work almost one-to-one. The only exception is that my buffer titles aren't highlighted.