kernel: changed main thread priority to default, updated Kernel::Reschedule to use PrepareReschedule

svc: updated waitSychronization to not overwrite handle on return, added stub for SleepThread (does nothing)

thread: updated Reschedule to sit at a synchronization barrier when no other threads are ready for execution

event: added a hackish ability to set an event as "locked" to its current state, cleaned up some comments

- force kernel reschedule after svcWaitSynchronization
- fixed some bugs with passing in pointer arguments
- cleaned up some comments and log messages

hle: removed PARAM64 macro (this was incorrect), made several bug fixes accordingly for decoding U64 function parameters