Zelda HLE: Convert some ERROR_LOG to PanicAlert.

While these are not really unrecoverable errors, while Zelda HLE is in a
testing / development phase it is useful to notice these "unexpected" cases (or
expected without known ways to reproduce) by making them as hard as possible to
ignore.
Zelda HLE: Properly implement the square wave generation.

Zelda TWW magic meter works properly now.