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.

Note that this comment refers to strtol whereas the call made is to strtoll.  Stylistically, I wouldn't capitalize the name of the routine just because it starts a sentence.  I'd also write it with parens or single quotes (or both) to better indicate that it's a function/code element:  e.g., "strtoll() converts the string to a ..."