creating tabline theme

WORK IN PROGRESS !!
Merge remote-tracking branch 'upstream/master'

Merging bling's upstream into my fork
basic working independent inactive modified highlights.
use airline_c for better predicability.
check existence of inactive modified colors before using them.
fill in inactive modified colors.
show hidden buffers with a different color. resolves #229.
Luna theme support for Tabline

Slightly better theming, than the automatically genenrated one by
Airline.
Merge pull request #231 from Pychimp/master

Luna now supports Tabline :)
basic working independent inactive modified highlights.
use airline_c for better predicability.
check existence of inactive modified colors before using them.
fill in inactive modified colors.
show hidden buffers with a different color. resolves #229.
Merge branch 'master' into dev
implement customizable file name formatting (#230).
turn on deprecation warnings.
extract buffer name logic into a formatter.

hold off on deprecation warnings for now...
pass in buffers to the formatter.
take window size into account before restricting the limit.