Reviewed-by: tschatzl, jwilhelm

Summary: Check that native memory is returned to the system when decommiting memory within the heap with G1.
Reviewed-by: tschatzl, jwilhelm
Contributed-by: NAndrey Zakharov <andrey.x.zakharov@oracle.com>

Summary: Implementation of JEP 192, http://openjdk.java.net/jeps/192
Reviewed-by: brutisso, tschatzl, coleenp

Summary: When G1 is run with -XX:-G1DeferredRSUpdate, the VM crashes because of wrong initialization order of member variables. The change makes the initalization explicit, not relying on initialization order any more.
Reviewed-by: brutisso, mgerdin

Summary: Extract the G1ParScanThreadState class from G1CollectedHeap.?pp into its own files.
Reviewed-by: brutisso, mgerdin