Run command no longer overwrites document

Previously the run command would take care of saving the document rather than rely on TextMate to do this. The reason for this was to allow executing untitled documents as scripts (without asking the user to first save the script).

With TextMate 2 we no longer ask for a file name when using the “Save: Modified Documents” option, so the run command now only takes care of saving, if the document is untitled (in which case, it writes it to a temporary file and executes that).
Use TextMate.save_if_untitled from bundle support
Update stack trace hyperlinking

We no longer test for untitled documents since these are transparently handled by TextMate.executor.
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.