This commit adds a relatively complete test case for the `path_link`
syscall. This commit should serve as some prep work for implementing
`path_link` on Windows (which will follow in a subsequent PR).
* General Cargo.toml cleanup.
- Remove travis-ci attributes.
- Remove "experimental" badges from actively-developed crates.
- Reflow some long lines.
- Use dependency features consistently.
- Add readme attributes
* Update WASI to the latest trunk.
This notably adds a .gitignore file for the WASI directory.