Collapsing code by selecting a range to collapse in the gutter.

Issue #1109

Closes #1106

closes #993

There is no reason for styling intended for lines to affect the cursor.

Issue #1053

Closes #1102

Closes #1098

Closes #1095

Issue #1094

For cheaply adding extra styling without going over
the whole document and doing markText.

Issue #1069

Saves some work for modes that don't have a startState method.

It may have been a widget that was removed and put back again, thus
losing focus.

Issue #1094

Firefox complains throws warnings when "Strict Mode" is turned on. This pull request fixes two of those:

    Warning: TypeError: variable data redeclares argument
    Source File: chrome://sieve/content/libs/CodeMirror/lib/codemirror.js
    Line: 845,Column: 8
    Source Code: var data = data || measureLine(cm, line), dir = -1;

    Warning: TypeError: variable spec redeclares argument
    Source File: chrome://sieve/content/libs/CodeMirror/lib/codemirror.js
    Line: 2870, Column: 8
    Source Code: var spec = CodeMirror.resolveMode(spec);