- Added the set_nth_bit & reset_nth_bit methods.
 - Added all 16 bit arithmetic instructions.
- Removed old code.
- Removed unnecessary __init__ from Z80ByteRegister & Z80FlagsRegister.
- Moved _set_nth_bit & _reset_nth_bit to Z80Register class.
 - Added bit, set & res instructions.
 - Added all regexps.
 - Added the arch module. It defines some common constants for other modules.
 - The sizes defined in the arch module are now used.
 - Added _log() method.
 - The sizes defined in the arch module are now used.
 - The sizes defined in the arch module are now used.
 - Irrelevant changes to constants.
 - Added cpu control registers.
 - Added the _translate_logging_args() method.
 - Added jump instructions.