Add octal literals

This adds support for octal literals in the compiler.  Additionally, adds three passing tests: one for the most
common case, one that include the capital O version (0O instead of 0o), and one that checks a bad octal is
rejected.  It also adds a feature request for the ability to print formatted output with octals within it.

Given the simplicity of this test and the time required to compile two short tests vs. one slightly longer test, I'd combine these lower and upper case tests into one.