Rename AwesomeRenderer to PangoMarkupRenderer

Awesome WM uses the Pango Text Attribute Markup Language
(http://developer.gnome.org/pango/stable/PangoMarkupFormat.html), and
since other applications and window managers may use the same markup
language it's better to have a common renderer for this markup language.
Pad powerline segments with no-break spaces

Some applications using Pango and/or Cairo draw square unknown character
glyphs next to divider glyphs instead of regular spaces. Non-breaking
spaces resolves this issue, and they are probably more correct to use
(no application should break lines at the padding spaces since they
"glue" the segment and dividers together as one unit).

This commit appears to work fine in all supported applications on Linux.

This commit resolves the gvim font rendering problems mentioned in
issue #113.
Fix vim matcher string comparison

Refs 2f361711febaa822e4eb221f809b710cd650bf5b.