This is the newest version that doesn't use let (which we don't support).

Also, change the argument processing the use -L: to prepend the load path
and -l: to append.

This update required disabling support for:
Arrow functions (the => 'operator')
Mega strings (The ` and ${} things that are SO AWESOME)
And the following newer standard objects:
DataView, Generator, GeneratorFunction, Intl, Map, Promise, Reflect, Set,
Symbol, System, WeakMap, WeakSet