Add ability to specify a Stylesheet when rendering to reStructuredText

Rendering a note written in reStructuredText is a nice feature but
the default stylesheet, the one included in docutils, is not likely to
suit everyone's needs.  This commit enables the user to specify a
stylesheet to use when rendering the reST formatted note.  It adds one
new configuration parameter, rest_css_path, the full path to the
user's stylesheet.  The stylesheet is embedded into the reST-rendered
page.  Customizing the stylesheet allows users to do customizations
that enhance the notes.  My motivation for this change was to enable
the use of 'strikethrough' text on list items that have been
completed.
Merge pull request #28 from stefanv/font_size

Dynamic font size changing
Merge pull request #29 from ewalstad/master

Add ability to specify a Stylesheet when rendering to reStructuredText
Fixed unicode filenames

- Fix for unicode characters in text note filename.
- type in nvpy-example.cfg
Merge pull request #32 from swestdijk/iss30

Fixed unicode filenames
tags = None was tripping up tag searching

Have now fixed with extra check. Fixes issue 34, thanks for reporting
https://github.com/bayonne
Merged with tip
Fixed default font size setting
Implemented new gstyle search method
filter_notes methods return search regexp for UI

different notes filtering methods should return a single regular
expression that can be used by the content view to give visual feedback
on the found strings. I've implemented this for both the regexp and
gstyle search modes.
Search mode configurable
Implemented case-insensitive gstyle search
Removed hg-specific files
search mode and case sensitivity runtime changing

Added ttk.OptionMenu and Checkbutton to the search interface. You can
now change both the search mode, between gstyle and regular expresssion,
and the case sensitivity at runtime. Search results will be
recalculated.
Fixed tag completion

- Let tag completion work with the new search method
- set the search option to fix width, search entry was changing
- add the background option to nvpy-example.cfg
Merge pull request #35 from swestdijk/tag_completion

Fixed tag completion
Documented new gstyle search mode in README
Added change note for v0.9.3
Increased VERSION to 0.9.3
Added note about python-ttk on crunchbang linux

Thanks to Stefan Storåkers for reporting this.