Add a lexical parser for MySQL grants to the MySQL module. Change the be...

...havior of the grant-checker to use this new method by default and fallback to the strict method if it fails.

DO NOT BLINDLY MERGE.

@thatch45 This changes the default behavior of the MySQL grant checker to be what I consider to be the correct method. A discussion of this issue is in #5817 and I think it may affect some other open bugs as well, though I don't have those in front of me at the moment. 

I consulted with @basepi and he advised that backward compatibility should not be an issue here but I'd also like you to weigh in, of course. Thanks!