Cleaning up references to mDragView after reordering Workspaces

Change-Id: I480142b4714034c5579232a6a0d30f3aecb687ac
Fix NPE if a moved cell does not have a parent

This NPE should actually never happen. It did however and crashed
Trebuchet.
Symptom that will lead to this NPE: Drag Shortcut from homescreen
to somewhere else. Old icon will not get removed while dragging.
This should also be fixed!

Change-Id: I5b5070c93077e69f0f63a26d337fb9aee83ec6d2
Folders: Merge Folders

This allows a folder A's contents to be merged into folder B
when folder A is drag/dropped onto folder B.

Change-Id: I41d62d04b6b4f0932cc68fb6d2a3be111b063d53
Trebuchet : Fix overscroll overlay issue

When overscrolling in the app drawer, certain effect/page combinations
cause the pages to be overlayed.

Reproduction :
- Have 2 pages in the app drawer
- Set scroll effect carousel,rotate up/down
- Overscroll one of the pages and let it settle
- Should see first and second page stacked together

Change-Id: Iaa2b06970e2f5d3dda51ce5bf2259523738f7779
Merge remote-tracking branch 'cm/cm-11.0' into cm-11.0