More flexible connection support and removal of annoying printf-statements

Hello Carl,

I had to do some surgery on a legacy MySQL database at work, so I decided to try this with CHICKEN. Unfortunately, I immediately ran into the problem that the database was living on another server, to which I was connected with SSH using port forwarding to a nonstandard port, as I was also running MySQL on my development box. The egg had no way of supplying a nonstandard port. Since this was easy to add, I added it :)

After that, I got annoyed by the printf statements messing with my program's output, so I decided to convert these into proper error reporting using a custom Scheme exception object. I've updated the tests to be a little more robust as well, and added some verification tests that results are fetched correctly.

I think the test suite can still use some work, but I think this should make the egg a lot more usable. If you decide to accept this pull request, please consider tagging and pushing a new release.

Kind regards, Peter Bex (sjamaan on IRC)