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
Added new color theme: Kalisi
Merge pull request #428 from eyetracker/master

Added new color theme: Kalisi
Add new color theme: hybrid
Merge pull request #434 from yasuoza/hybrid-theme

Add new color theme: hybrid
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
Clarify doc for loading custom extensions
minor doc fix: s/various some/various/
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
improve whitespace detection. resolves #452.
Fix "Cannot use empty key for Dictionary" error

This commit resolves compatibility issue with fugitive plugin. When
using "Gdiff" command on some file, fugitive attempts to open the
current and the index version of the file. For example, if the file is

    /home/taketwo/path/to/the/project/README.md

then fugitive will use the following path to open the index version:

    fugitive:///home/taketwo/path/to/the/project/.git//0/README.md

Opening this file leads to a cascade of errors like this:

    Error detected while processing function
    airline#extensions#tabline#get..<SNR>162_get_buffers..<SNR>162_get_visible_buffers..airline#extensions#tabline#get_buffer_name..airline#extensions#tabline#unique_tail_improved#format:
    line   20:
    E713: Cannot use empty key for Dictionary

The problem is that when a filename like this is being tokenized, there
appear empty "" tokens, and an error occurs when using them as keys in
`path_tokens[token_index]` dictionary. This fix simply skips empty
tokens.
Merge pull request #455 from taketwo/fix-empty-key-error

Fix "Cannot use empty key for Dictionary" error
Customizes tabline appearance: type, close button

This commit adds a couple of new settings so that it's possible to hide
the tab type (all the way to the right) and the symbol which represents
the close button.

The settings and their defaults:

let g:airline#extensions#tabline#show_tab_type = 1
let g:airline#extensions#tabline#close_symbol = 'X'
Improve colour highlights

- Sol: Used a less distracting color to show a modified file/buffer
- Sol: Similar change as above, to tabline as well
- Sol: Warning colour imporved (Previously was some bad shade of magenta)
- Sol: All the Above mentioned changes replicated for CTERM values as well
--------------------------------------------------------------------------
- Luna: `Inactive Modified` colour is improved (Was a shade of red
                                                that was hard to read)