- reorganized some kernel thread functions
- added placeholder __KernelWaitThread_Synchronization function

- added KERNEL_DEFAULT_STACK_SIZE definition (0x4000)

- added __KernelSwitchToThread for enabling a thread
- added __KernelRotateThreadReadyQueue

added a bunch of threading code, recycled from PPSSPP, with lots of hacks in for 3DS... doesn't really do much yet. Just a jumping off point