Fix crash when deleting ShellSurface objects

We must not leave dangling wl_resource objects with their
user data pointing to a deleted object.

Change-Id: I54aa7f03bc7542fdea144dd0af8da7f600b4d21c
Add a way to create server-side only surfaces
WIP hardware compositor APIs
WIP hardware compositor...

Change-Id: Iaa9856d6c7c8da8d002e09988195ee551d85d255
WIP: more hwcomposer work

Change-Id: Id2daa95609f8fb53b6d83e7a14597c38c4b3b6df