Closes #1133

Multi-line Lua comments start with "--[[", not "--["

Add CodeMirror.defineOption function for defining new options.

Add findMatchingBracket to the methods exported by this extension.

Closes #746

Since v2 is the canonical CodeMirror at this point

So that I can put other doc-related stuff there without polluting the
root dir.

Replaced "for" and "while" in indent tokens with "do".  This is not only simpler, but allows for correct indentation when "do ... end" blocks are used (these are valid; see the complete syntax of Lua: http://www.lua.org/manual/5.1/manual.html#8 ).

Indentation bug fix related to multi-line comments and multi-line strings.  Previously if a multi-line comment or string contained the word 'end', it would throw off the indentation level for all following code.

This normalizes the classes used by most of the modes
(reStructuredText and diff didn't fit in), and makes them all
reference a central style sheet (under theme/). It also adds a theme
option that can be set to change the theme, and defines a few
different themes (some based on old mode colors).