Pak files above 4GB caused the async file system to throw an error about failing to load audio banks, removed casts and promoted everything correctly. Also removed irrelevant comments in the public pakfile header.
* split rtech_game and rtech_utils cpp files into multiple files
* rebuilt several large pak load routines for debugging and custom implementations
* moved rson code to rtech_game
* reworked and improved engine and sdk pak precache system
* reversed more of the jobthreads system
