Add missing number base conversion functions (bin, oct, hex) to builtins

[JennaSys]

Add missing number base conversion functions (bin, oct, hex) to __builtin__.js Add autotests for new number base conversion functions to module_builtin

Addresses most of issue: https://github.com/QQuick/Transcrypt/issues/752 After this PR, I think the hash function is the only other missing built-in.