Massive efficiency and performance improvements

These are pretty much the same changes I made with netcaps 1.5.0 so I'm not going to elaborate a ton here.

• Caches IOHIDManager instance for dramatically better memory usage.
• Sleeps for a little bit when idle, shouldn't impact performance visibly, but will save some CPU cycles when the disk isn't being used (Probably never).
• Also, I didn't mention this in the netcaps changelog, so better late than never, but when running in silent mode, the priority is reduced, no clue what impact this will have so YOLO.