Almost decouple layouting and drawing in vty frontend.

Also fix jumping modeline.
Extract some layout code from Yi.UI.Vty into Yi.UI.SimpleLayout.
Try --force-reinstalls in attempt to fix travis build.
Remove some unneeded code.
Label main vty thread.
Move some more layouting code to Yi.UI.SimpleLayout.
Yi.UI.Vty now completely delegates layouting windows to Yi.UI.SimpleLayout

Still todo: extract layouting of tabbar items.
Merge remote-tracking branch 'origin/master' into vty-refactoring

Conflicts:
	yi/src/library/Yi/UI/Utils.hs
	yi/src/library/Yi/UI/Vty.hs
Allow frontends to submit multiple events at once.
Fix some warnings.
Now I'm just using travis to compile pango frontend.
One less boolean in API.
Trying to blindly fix pango again.
Simplify renderTabBar.
Styling.
Remove annotations.
Get rid of Yi.MiniBuffer.hs-boot

This setup make more sense anyway, maybe except the commentRegion
location.
Get rid of stale TODO (done now)
Get rid of Yi.Buffer.HighLevel.hs-boot
Remove unused streamB'.