Refactor CLI #43

The current CLI is a bit awkward since it was thrown together for the proof-of-concept. Sub-commands could help clean it up a good amount:

• postject inject <filename> <resourceName> <resource> [outputFilename] - the current functionality, but with optional output path
• postject inspect <filename> - shows you a list of resources injected in the executable
• postject view <filename> <resourceName> - shows you the contents of a resource
• postject output-api - dumps the C run-time API to stdout