PCT-1085

Fixes for slow log parser.
For PCT-1085 & PCT-1006
- Empty queries are not being sent in the response.
- Cheked "use", "uSe", etc
- Checked dbname in use between backticks.
- More than one "use statement" in a slow log file.
- Empty queries are not being processed by the fingerprinter.

How can this error/problem bubble up? This is always a fundamental design concern because we can't solve problems that we don't know exist. Here, however, we're so deep in the code (this is the bottom in fact) that I'm not sure how to make this problem known to higher code parts. Let's look and think some more on this...