Strip comments

[mindplay-dk]

We ported this from JS, so the library only supports splitting SQL statements at this time.

Since this is PHP, we'll be using PDO, which doesn't play well with comments.

The library should therefore strip comments from SQL statements.

[mindplay-dk]

On a related note, the library currently returns trailing comments (at the end of the file) as an individual query. (the original library does that - the tests didn't cover that case.)