Batch line marking operations to improve performance (especially on initial load).

Also, fix parseHtml() tests I broke with image support.
Provide an "entityHandle" to the entity render function that lets it later find the entity, remove it, or replace it.
Fixed EntityManager exportToElement
Changed args order for EntityManager tryRenderToElement_ to make entityHandle non required
Updated build
Fixed RTCM createEntityHandle_ support for remove with char at index 0
Update firepad.js
Enable self cursor tracking (basics for live toolbar update)
Build
Fix apply context/args
Build
Fix #58 Exception after removing entity.
Merge pull request #57 from LiveMinutes/fix_cursor

Enable self cursor tracking (basics for live toolbar update)
Add Google Group link to README
Issue 59: Allow 'getHtml' (instead of 'export') for exporting entities, since 'export' is a reserved keyword.
Merge branch 'master' of github.com:firebase/firepad
Fix #54.

* Don't apply text attributes to line sentinels.
* Do a better job of deciding what the "current" attributes should be when selection starts or ends on line boundaries.
Disallow drag/drop as a mitigation for https://github.com/firebase/firepad/issues/36
Support background color text formatting
Support all HTML entities from their node name