Don't use TM_RUBY for running Rake tasks

This still supports using `TM_RAKE` to set the version of rake to use when running tasks.
Support comment groups in regular expressions

Fixes #35.
Give full path to helper library

This is required in 2.0 as we longer augment the PATH with the bundle support bin folder. Fixes #56.
Make help command use APIDock.
Remove Ctrl-Shift-w keybinding (should call 'Wrap Selection' even in Ruby mode)
Make Ctrl-" toggle only between single and double quotes.

Treat %Q{...} as one of the 'more esoteric quote styles' (i.e. convert it to double quotes if Ctrl-" is used on it.
Fix invalid key binding that disables dead keys.

See http://lists.macromates.com/textmate/2012-September/035552.html
Simplify do...end snippet.

Make it easier to use for do...end blocks without block variable.
Simplify 'encoding: utf-8' snippet, use 'enc' as trigger.

utf-8 is the only encoding we use anyway, so no need to make it editable. And there should be no newline after the snippets, too.