Improve fontpatcher README

This commit adds a detailed guide to font patching for both Linux and OS
X users.

Closes #13.
Refs #20.
Update main README

Made the installation instructions clearer.

Refs #20.
Add theme appropriate for 16color solarized theme.

Got rid of a few sections I don't care about / don't use and made the remaining
color selections appropriate for the 16 color solarized color scheme from
Ethan Schoonover: ethanschoonover.com/solarized
Update fontpatcher README

Refs #13.
More color changes for solarized.

Moved some pieces around, made some of the colors more sensible.
solarized:add buffer #, change RO colors, add 'INS'
solarized: Add support for macvim and gui mode.

Replicate the 16 color solarized theme by creating our own 16-color
PL#Colors#cterm2gui() function that reutns the correct hex values
for 0-15 instead of RED like the parent function
Merge remote-tracking branch 'danielbeardsley/solarized_theme' into develop

* danielbeardsley/solarized_theme:
  solarized: Add support for macvim and gui mode.
  solarized:add buffer #, change RO colors, add 'INS'
  More color changes for solarized.
  Add theme appropriate for 16color solarized theme.

Closes #29.
Make sure that hi_curr is set in GroupHandler

Stored statuslines may skip highlighting for several modes so the
statuslines for these modes should be stored as empty statuslines
instead.

If mode highlighting is missing for a mode (e.g. noncurrent, insert),
hi_curr wasn't set and caused an error in GroupHandler. This commit
makes sure that the hi_curr varable is set and will remain empty if no
highlighting is provided in GroupHandler.
Allow storing statuslines by key

This commit adds two new functions, Pl#StoreStatusline() and
Pl#GetStoredStatusline(). Statuslines passed to Pl#StoreStatusline()
won't be applied to any buffer or window, but can be fetched in e.g.
a callback function with Pl#GetStoredStatusline().

Refs #25.
Create Ctrl-P statuslines

The custom_statuslines branch of kien/ctrlp.vim supports setting the
statusline through functions defined in g:ctrlp_status_func. This commit
introduces a working statusline for the Ctrl-P plugin.

Refs kien/ctrlp.vim#80.
Closes #25.
Tag the cache file with a revision number

Because of possible reformatting of the cache file in future versions,
the cache file will be tagged with a revision number. The statuslines
are regenerated if the cached revision number is missing or is different
from the current Powerline version's revision number.

Closes #5.
Create troubleshooting section in the README

Refs #13.
Closes #33.
Allow using NONE for statusline colors
Update highlighting for distinguished theme

The split section of inactive windows are now transparent.
Update docs with UTF-8 encoding setting

Refs #36.
Update symbol font
Make fontpatcher script work with the new symbol font
Fix fontpatcher to set proper width on new glyphs

Gvim on Windows seems to only considers a font to be monospaced if every glyph
has the same width; this setting appears to be unrelated to the glyph's
bounding box.
Allow fontpatcher to output TrueType fonts

Many TrueType fonts look like garbage if they are converted to PostScript
outlines. This change allows TrueType fonts to be generated back as TrueType
while any other format will be generated as OpenType.