* Rename the `wasmtime_api` library to match the containing `wasmtime` crate
Commit d9ca508f80 renamed the
`wasmtime-api` crate to `wasmtime`, but left the name of the library it
contains as `wasmtime_api`.
It's fairly unusual for a crate to contain a library with a different
name, and it results in rather confusing error messages for a user; if
you list `wasmtime = "0.7"` in `Cargo.toml`, you can't `use
wasmtime::*`, you have to `use wasmtime_api::*;`.
Rename the `wasmtime_api` library to `wasmtime`.
* Stop renaming wasmtime to api on imports
Various users renamed the crate formerly known as wasmtime_api to api,
and then used api:: prefixes everywhere; change those all to wasmtime::
and drop the renaming.
