A major overhaul to adopt to recent changes. It now passes all tests.

Note:
- All test results haven't been inspected in detail to see if they are correct.
- Some result set printing seems to have the wrong field width; most notably
  date/time fields and type fields (e.g. "int(4)").
- There are still some valgrind complaints, but they seem to be in assert() or
  in libmysql.