Implement Octo Extensions

[craigthomas]

Add the ability to parse Octo files and output Chip 8 binary code. The Octo extension is described in John Earnest's Github Wiki. The implementation of Octo should take place in two stages. In the first step, an Octo parser will be needed to translate high level language constructs into Chip 8 assembly patterns. For some commands, this should be straightforward. For example:

clear

maps cleanly onto:

CLR

More exotic constructs such as if ... begin ... else ... end require developing a template first, and expanding the code into the pre-defined template.