Refactor the compiler once again.

No variable scanner this time. This version will only feature a better macro interface.

Oh, and most extensions (as well as the REPL) don't work yet, as they are still to be adapted.
Invert a condition in argument parser.
Fix infix binding.
Restore missing parentheses.
Fix a couple of references.
Apply some fixes to `bootstrap`.

 * Import a missing module.
 * Use the correct method (`loadop`, not `opcode`.)
 * Fix byte-compilation of bootstrap code.
 * Allow to forcibly disable keyword arguments in `unpack`.
Make `conditionals` use the new API.
Port `unary` to the new API.
Port `binary` to the new API.
Fix yet another variable naming error.
Port `comparison` and `switch`.
Use `getattr` in case there is something non-FunctionType in PREFIX.
Don't wrap names in angle brackets if that's already done.
Port `inherit`.
Port `where`.
Port `loops`.

Honestly, this is the crappiest bootstrap module. Can I implement `iterate` in Python code and get rid of it? Probably.
Port `yield`.
Remove unused imports.
Port `functional`.

Ok, this one didn't need porting, I just moved `for` and `exhaust` here.
Port `unsafe`.

Ok, I don't even know how this one works. Not that I want to.