[octave mode] added more builtins, fixed comments

(removed non-octave ... comments, added octave's # comments)
Fix resolveMode's handling of MIME types in name fields

Also configure the htmlmixed option to pass through xml-mode-specific
options to its inner xml mode.

Issue #2265
Make by-group motion stop after groups of 1+ space, newlines

Issue #2255
Use a transparent border on the sizer to force scroll width

This produces saner widths for most elements, and removes
the need for the border/fit-width hack on the pre elements.

Issue #2256

Conflicts:
	lib/codemirror.js
[vim] More escaping fixes

1) Fix a bug whereby multiple '\'es in the replace part of a search and replace
string were getting collapsed into a single one.
2) Split flipEscaping into two specialized functions -- one for the regex part,
and one for the replace part.