OCD

Change-Id: Ia8b9f3b6a70a55fbf4f6f214c445a33493f58940
[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 :)

Change-Id: I1ac17d4124da420ba4e4c20401c3c54d11f4dfcb
More Multi-window stuff

Change-Id: Ibbf6f712fb9c2c0ad1acb8875770c12732231de2