* Reorganize wasi-misc-tests.
Move wasi-misc-tests out of wasi-common, to break a dependency cycle;
previously, wasmtime-* depended on wasi-common, but wasi-common
dev-dependended on wasmtime-*.
Now, wasi-common no longer dev-depends on wasmtime-*; instead, the
tests are in their own crate which depends on wasi-common and on
wasmtime-*.
Also, rename wasi-misc-tests to wasi-tests for simplicity.
This also removes the "wasm_tests" feature; it's replaced by the
"test-programs" feature.
* Update the CI script to use the new feature name.
* Update the CI script to use the new feature name in one more place.
* Change a `write!` to a `writeln!`.
* 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.
