Use QMultiMap instead of wl_list for resources

Change generated code in qtwaylandscanner to generate resourceMap()
methods returning a QMultiMap<wl_client*, Resource*>. Adapt code using
resource lists to use the map instead.

Remove Compositor::resourceForSurface().

Change-Id: Id41a1712f9c2477c1a1af843bba2795dd90391e5
Reviewed-by: Andy Nichols <andy.nichols@digia.com>
Reviewed-by: Andrew Knight <andrew.knight@digia.com>
Fix scanner to support also hex values in enums

Read the value of an enum entry as a QByteArray. There is not any
need to convert it into an int in between.

Change-Id: Ie75d30dc22f7e81ddcff64990e3c6f030f31ef79
Reviewed-by: Andrew Knight <andrew.knight@digia.com>
Reviewed-by: Andy Nichols <andy.nichols@digia.com>