Python 3 extension for interface with Wasmtime/Cranelift.
First, you'll need to install some Python dependencies:
```
$ pip3 install setuptools wheel==0.31.1 setuptools-rust
```
Next you can build the extension with:
```
rustup run nightly python3 setup.py build
```
Note that a nightly version of Rust is required due to our usage of PyO3.
This will create a directory called `build/lib` which you can add to
`PYTHONPATH` in order to get `import wasmtime` working.