[WIP] Multi-window

This is a big work in progress, which currently has some bugs,
but begins to look okay.

You can already multitask a little bit, by using the
app switcher and long-pressing an icon, then select "Add to
Split View".
Last window touched gets the key focus.

Still are some issues with rotation handling - touch an app
after rotation to make it relayout.

Enjoy :)

Patch Set 19

Change-Id: I4a03a84539fd3ac1273f0d3503fe8fafcd16be26

Conflicts:
	core/java/android/app/Activity.java
	core/java/android/app/IActivityManager.java
	core/java/android/content/Intent.java
	core/java/android/view/IWindowManager.aidl
	packages/SystemUI/res/values/custom_strings.xml
	packages/SystemUI/src/com/android/systemui/recent/RecentsPanelView.java
	services/java/com/android/server/am/ActivityStack.java

Conflicts:
	core/java/android/app/IActivityManager.java
	core/java/android/view/IWindowManager.aidl
	packages/SystemUI/res/values/cm_strings.xml
	packages/SystemUI/src/com/android/systemui/recent/RecentsPanelView.java
	services/java/com/android/server/am/ActivityStack.java
fix derps

Change-Id: I82d4d75ba0a5031bbb56a3c4583db4f48438f70e
Merge branch 'jb-mr2' of https://github.com/TeamHorizon/platform_frameworks_base into testing

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

Change-Id: I6b6f7107183f16bac581fa0a3e113bf9c60be862