Syntax Rejiggering

Couple of small changes:

1. Static access now uses :: instead of ., along the veins of C++ and Rust.
2. Polymorph instantiations now take the form of Foo!<...> (the exclamation mark) -- making it less likely to be ambiguous.
3. Polymorph arguments can now be positional, meaning Foo!<int> instead of Foo!<T: int>. The rules are similar to that of funtion calls -- no positional arguments after named arguments.