* Started to rewrite the thread scheduler
* Add a single core-like scheduling mode, enabled by default
* Clear exclusive monitor on context switch
* Add SetThreadActivity, misc fixes
* Implement WaitForAddress and SignalToAddress svcs, misc fixes
* Misc fixes (on SetActivity and Arbiter), other tweaks
* Rebased
* Add missing null check
* Rename multicore key on config, fix UpdatePriorityInheritance
* Make scheduling data MLQs private
* nit: Ordering
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