Created avutil directory for avutil.h headers
List of things changed:
	low/avutil new file to contain avutil parts
	
	headers/dict: moved to headers/avutils/dict available from
headers/avutils if you need it.
	low/avdictionary: removed, contents now
in low/avutil

	headers/avcodec: Added a huge bunch of definitions
	headers/avformat: Added a huge bunch of definitions
	
	low/avcodec: Added wrappers for various types and cleaned up.
	low/avformat: Added wrappers for various types and cleaned up.