Created the NSMutableCopying protocol.
Created the NSCopying protocol.
Imported NSCopying.h to WCSFraction.h
Imported NSMutableCopying.h to WCSMutableFraction.h
Restarting prog 2.f
Made WCSFraction.h adopt the NSCopying protocol.
Made the WCSMutableFraction.h adopt the NSMutableCopying protocol
Wrote the code for WCSFraction.m and WCSMutableFraction.m for copyWithZone and mutableCopyWithZone.