memory.cpp/h contains definitions related to acessing memory and
configuring the address space
mem_map.cpp/h contains higher-level definitions related to configuring
the address space accoording to the kernel and allocating memory.

Instead just use nullptr to represent no thread is active.

The TLS area for thread T with id Ti is located at TLS_AREA_VADDR + (Ti - 1) * 0x200.
This allows some games like Mario Kart 7 to continue further.

SVC: Return correct error code on invalid CreateThread processor ID.

SVC: Assert when creating a thread with an invalid userland priority.

Involves making asserts use printf instead of the log functions (log functions are asynchronous and, as such, the log won't be printed in time)
As such, the log type argument was removed (printf obviously can't use it, and it's made obsolete by the file and line printing)

Also removed some GEKKO cruft.

* Simplifies scheduling logic, specifically regarding thread status. It should be much clearer which statuses are valid
for a thread at any given point in the system.
* Removes dead code from thread.cpp.
* Moves the implementation of resetting a ThreadContext to the corresponding core's implementation.

Other changes:
* Fixed comments in arm interfaces.
* Updated comments in thread.cpp
* Removed confusing, useless, functions like MakeReady() and ChangeStatus() from thread.cpp.
* Removed stack_size from Thread. In the CTR kernel, the thread's stack would be allocated before thread creation.

They're finally unnecessary, and will stop cluttering the application's
handle table.

During normal operation, a thread waiting on an WaitObject and the
object hold mutual references to each other for the duration of the
wait.

If a process is forcefully terminated (The CTR kernel has a SVC to do
this, TerminateProcess, though no equivalent exists for threads.) its
threads would also be stopped and destroyed, leaving dangling pointers
in the WaitObjects.

The solution is to simply have the Thread remove itself from WaitObjects
when it is stopped. The vector of Threads in WaitObject has also been
changed to hold SharedPtrs, just in case. (Better to have a reference
cycle than a crash.)

This should speed up compile times a bit, as well as enable more liberal
use of forward declarations. (Due to SharedPtr not trying to emit the
destructor anymore.)

This is to support the removal of GetHandle soon

Remove unnecessary/unused struct variables.

- ReleaseNextThread->WakeupNextThread
- ReleaseAllWaitingThreads->WakeupAllWaitingThreads.

- Separate wait checking from waiting the current thread
- Resume thread when wait_all=true only if all objects are available at once
- Set output to correct wait object index when there are duplicate handles