Implement perfstats options for LUAh_PreThinkFrame and LUAh_PostThinkFrame

When I initially added the PreThinkFrame and PostThinkFrame hooks, I wasn't aware that perfstats measured ThinkFrame, and thus PreThinkFrame and PostThinkFrame lacked any good way to measure them. This merge request fixes that by adding new options to perfstats: PreThinkFrame/4 measures PreThinkFrame hooks, PostThinkFrame/5 measures PostThinkFrameHooks. I have decided to leave ThinkFrame/3 where it is as to not confuse people currently using perfstats to measure ThinkFrame.

Using the latest git copy of MRCE as an example...

ThinkFrame:

PreThinkFrame:

PostThinkFrame: