- Provide `ignores` option in depcheck command line utility.
- Show help message in depcheck command line utility.
- Store the directory that cannot access to `invalidDirs` property in the JSON output. (Check the [test case](https://github.com/lijunle/depcheck-es6/blob/58fed0956e05047df87d826afecde414eaa99688/test/index.js#L183-L202) for more information.)
- Speed up check when there is no dependencies and dev-dependencies installed.
- **Fix** the bug about storing parse error files to `invalidFiles` in JSON output.
- **Breaking change**: the depcheck option will not pass to acorn parser. This functionality will be provided in the [pluggable desing](https://github.com/lijunle/depcheck-es6/issues/27) in the next release.