y_hooks compatability and tag fixes.

Moved some functions about to avoid reparse warnings and fixed a function parameter tag.  I also added a function to re-get an amx file's header in case some code decides it wants to mangle it (as the sort of code that uses a library like this might).  Frankly I'm not sure how to separate the changes in asm.inc (pure fixes) from the changes in amx_header.inc (frivolous features only I need), so pull what you want if you can.