Removes a TODO.

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.

It was only being used in two places, where it was replaced by a local
constant.

- Would deadlock the calling thread
- Code would never get hit anyways

- 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

Logging: Log all called service functions (under trace). Compile out all trace logs under release for performance.