Revert "multiwindow: Fix NullPointerException"

This reverts commit 257ead4b21716de555b8eaf3104afe21600f395a.
Revert "mutliwindow: notify split view if layout changed [2/2]"

This reverts commit 56bbc008d09b98643ed92000f54bfbe0cf5a43f0.
Revert "mutliwindow: notify split view if layout changed"

This reverts commit abd69891a7c6fea386ef3a833a9e8eb5975325fd.
Revert "HALO notification should open in floating window mode"

This reverts commit a6ec482f27da5b5f2e6fe7b90104902461e16326.
Revert "prevent multiwindow if halo enabled"

This reverts commit 5bd2e6342623237c1a70dd9e925f4a461c6151c7.

Conflicts:
	core/java/android/inputmethodservice/InputMethodService.java
Revert "Multi-window support"

This reverts commit 7dd272e331b37b0e92974af2fab7ab523c95871c.

Conflicts:
	core/java/android/view/IWindowManager.aidl
	packages/SystemUI/res/values/cr_strings.xml
	packages/SystemUI/src/com/android/systemui/recent/RecentsPanelView.java
	services/java/com/android/server/am/ActivityStack.java
	services/java/com/android/server/wm/WindowManagerService.java