This allows multiple handlers to listen for a single event, and makes
the API a bit more uniform.

Issue #725

- Multiple gutters are explicitly created with the gutters
  option
- Markers go into a specific gutter, new setGutterMarker,
  clearGutter methods
- The line number gutter is separate
- The 'fixedGutter' feature is removed (painful to do now,
  was shaky anyway)

This fixes the problem where the tabs interfere with other text when only
a single character wide.

Issue #673

Courtesy of Mike Griffin

Use this in the VIM mode to make the cursor wide in escape mode.

This makes it easier for alternative keymaps to hook into it.

Standardize theme, add links to front page and compression helper.

Closes #409

Add Match Highlighter add-on to lib/utils, a new demo showing it off, and modify index.html to link to the demo

When exiting fullscreen: fallback on width and height set by css instead of recalculating, which was wrong anyway, when pressing F11 a couple of times the editor would decrease in width.

Removing dependency on jQuery, only allow `Esc` to *exit* full screen (rather than *toggle*), and changing class name to be consistent with CodeMirror class naming practices.