svc: added stub for DuplicateHandle SVC call
kernel: add a SyncRequest method to KernelObject for use with svcSendSyncRequest
svc: changed SendSyncRequest to use Kernel::Object SyncRequest (instead of just service Interface class)
srv: added a real mutex for GetProcSemaphore (instead of stubbed)
kernel: added enum for known CurrentThread and CurrentProcess handles
service: Renamed Sync to SyncRequest
svc: added some assertions
kernel: updated SyncRequest to take boolean thread wait result as a parameter
kernel: added WaitSynchronization method to Kernel::Object
mutex: added additional docstrings
mutex: removed docstring comment that is no longer relevant