Added a new function that returns a file extension associated with a mime type while supporting wildcard asterisk character in either the toplevel or sublevel type.
Merged extensionWild with extension.
Added function compare(a, b) which checks if too mime types match exactly or overlap. Added test cases in test.js to test this. Everything works well.
Merge branch 'compare'
Removed two redundant lines in compare(). All tests pass. Ready to submit a pull request.