Multi-window support

Change-Id: Ie5860c2105ad9c971157b41d65f8fab337461ef6

Conflicts:
	core/java/android/app/Activity.java
	core/java/android/content/Intent.java
	core/java/android/inputmethodservice/InputMethodService.java
	core/java/android/view/IWindowManager.aidl
	packages/SystemUI/src/com/android/systemui/recent/RecentsPanelView.java
	services/java/com/android/server/wm/WindowManagerService.java
prevent multiwindow if halo enabled
please multiwindow stay out if HALO there !! , but we will leave you in activity

Change-Id: Ie9ca36b6c7647ff9c6f038986b107f3623d8726c

Conflicts:
	core/java/android/inputmethodservice/InputMethodService.java
	packages/SystemUI/src/com/android/systemui/recent/RecentsPanelView.java
multiwindow: Fix NullPointerException

Change-Id: I5c423bcde7d191331be53ce180f827e7023dc472

Conflicts:
	services/java/com/android/server/am/ActivityManagerService.java