Update ExtJS to latest 3.4.* release

This works pretty without any change.
There is now better IE support.
Merge pull request #430 from cookiekiller/extjs_update

Updates ExtJS to latest 3.4.* release
Merge pull request #431 from cookiekiller/scrolling_fix_chrome

Fixes scrolling issue in Chrome / Chromium / Webkit
Implement concrete itemUi classes for lists and trees
Implement AbstractListItemUi for every itemUi opened by a listUI
Implement AbstractTreeItemUi for use by treeUi
Forward TreeUi action and scope to AbstractTreeItemUi
Clean up new Abstracts and move code
Remove some old @todo