Implement z-order bias for touch handling

[totallyeviljake]

when touch handlers overlap on the screen the touch events are sent to all of them. the touch should be handled in a z-order fashion where the top most node gets to process the touches and discard them if they are not in the node.

[totallyeviljake]

Please implement this soon. We see this manifest always in some ccflash tests.

[totallyeviljake]

I have added support for this in the following commit:

1155036

You enable it by using the CCConfiguration class (CCConfiguration.UseGraphPriority)

[totallyeviljake]

My last commit 5e0fb08 is making the graph priority work more reliably. I still see some oddities in the graph dispatcher, but mostly this is working as expected. CCControl had some hard coded priority values (1) and overrode some behavior that did not make sense.

[totallyeviljake]

The first attempt at fixing this did not work properly. So I implemented read graph order indexing of the touch handlers.

ae5b663