Fixed some compiler warnings
Started main clean-up of version 1.6

* Fixed all compiler warnings
* Killed union usage
* Started using C99 fixed width types
* Started normalization of whitespace width in listing
* Simplified internal addresses computations
Refactored disassembly code to combine steps
Greatly simplified disassembly code
Simplified hex value conversions for args
Started version 2.0

* Simplified mnemonic name lookup
* Started refactor of argument parsing
* Converted addressing modes to an enum
* Renamed poorly named variables