solarized: use VertSplit bg for inactive statusline

Adjust foreground color accordingly, also for non-active modified
filename (to stand out).
Revert changes to s:NM, add s:NMi for inactive windows
tagbar: only lookup tag once every second

This makes scrolling (holding done j/k) much smoother, and the current
tag gets pulled in via CursorHold anyway.

Fixes https://github.com/bling/vim-airline/issues/387
Merge pull request #441 from blueyed/tagbar_once_per_second

tagbar: only lookup tag once every second
Correctly detect mercurial repos using lawrencium
Enable branch extension when vcscommand is available
reset current buffer when one gets deleted. resolves #399
Merge pull request #404 from blueyed/solarized-inactive-like-vertsplit

solarized: use VertSplit bg for inactive statusline
Merge pull request #410 from coven/master

Branch extension bugs. Fix #444