Support indented fenced code blocks
Fix highlighting HTML entities at start of line
Support blank lines in block quotes
Clear `main_syntax` if we set it.

This prevents conflicts with other syntaxes that use `main_syntax`, like
vim-javascript.
Highlight italicized regions within bold regions
Merge pull request #38 from hjdivad/dont-stomp-main-syntax

Clear `main_syntax` if we set it.
Merge pull request #41 from cemerick/master

Highlight italicized regions within bold regions
Allow spaces after ```

With a fenced code block with a language, it's legal to put spaces
between the fence and the language name.
Merge pull request #45 from AndrewRadev/fix-fenced-code-block-pattern

Allow spaces after ```
implement syntax highlighting of CM's add, delete and substitute
add plugin files for criticmarkup
fix matching of criticmarkup when whitespace is involved
implement CMHighlight and CMComment and pick neutral colors
Changes {{}} to {====} highlight style
Adds --,++,~~,==,<< snippets to easily create edits
Adds surround.vim bindings for all types of edits
Merge branch 'cormacrelf'
Convert snippets to Ultisnips format