Adding support for action specific message handlers. This will enable message coalescing, message routing, and any other arbitrary message preprocessing.
Starting to work on fixing #725: Restore original thread priority on resume
More fixes to default priority handling
Extending API to get count of threads by priority
interval_timer now creates high priority threads
Making sure priority of thread at the point of scheduling is properly reflected in the thread state.
Added this_thread::get_priority() API
Added test verifying fix #725: Restore original thread priority on resume
Merge branch 'fixing_725'

Conflicts:
	tests/performance/hpx_homogeneous_timed_task_spawn.cpp