Make sure gutter is redrawn when a document is shifted

Issue #2498
[compression helper] Use CodeMirror for code field

Dog food, and all that.
[runmode addon] Pass state to blankLine

Issue #2502
[foldcode addon] preventDefault clicks on widgets

So that the click doesn't kill editor focus.

Closes #2505
[haxe mode] Line comments for Hxml
[vim]: IE8 fixes.
 - avoid array .indexOf - fixes % key and non-pcre searches.
 - avoid array .map - fixes a couple of non-running tests.
[shell mode] Fix empty token bug

Issue #2506
[vim] Fix bracket matching off-by-one
[shell mode] Add tests.  Not very thorough but touch most functionality.
Support expected fail mode tests.  Add a few for shell mode.
[shell mode] Fix highlight of spaces after variables in double quoted strings.
[shell mode] Fix number highlight at end of line.
[shell mode] Understand backslash escaping outside strings.