Switch to binary/library architechture

[Razican]

We currently have a whole binary crate for SUPER, which makes integration with other tools really difficult (if not by running a separate command). We should switch to having a binary (in src/bin.rs) and a library (in src/lib.rs), each with different names, so that we can publish the library in crates.io (and even the binary) and use that library from external tools directly.

This of course has little benefit while we still have Java dependencies.