Omni: Floating window with multitasking

https://gerrit.omnirom.org/#/c/6380/
Base: Floating window with multitasking
basic floating window are taken from AOSPA (HALO) by @D4rKn3sSyS
Drawables courtesy of @Alex Cruz thanks to him :)
with heavy change to get this work for multitasking
this feature, has ability to:
1. Moveable window to various position
2. Scaling window with 2 finger like zoom in/out
3. Double tap in actionbar or above window to fullscreen or back to floating window
4. Automatically resize when Snapping into one of side (Top, Bottom, Left, Right)
   (taken from xhalofloatingwindow by @zst123)
5. Automatically switch focus from other app (taken from multiwindow by @xplodwild)
6. Unlimited floating window app (depends on RAM)
this is still under testing, to make fully works
so if there any bug because of this, DO NOT REPORT INTO OMNIROM JIRA
to make app launch using Floating window feature
you must add Intent.FLAG_FLOATING_WINDOW
before start an activity.
for example you can look at http://review.pac-rom.com/1774

Change-Id: Iad00c239de7d66e8bb45205ce626d4f08417b7cd

Conflicts:
	core/java/android/content/Intent.java