Closes #1139

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.

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

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

- 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