This commit removes the need to use `HostRef<Engine>` in the Rust API. Usage is retained in the C API in one location, but otherwise `Engine` can always be used directly. This is the first step of progress on #708 for the `Engine` type. Changes here include: * `Engine` is now `Clone`, and is documented as being cheap. It's not intended that cloning an engine creates a deep copy. * `Engine` is now both `Send` and `Sync`, and asserted to be so. * Usage of `Engine` in APIs no longer requires or uses `HostRef`.
Python 3 extension for interface with Wasmtime/Cranelift.
Build
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.