- Added version checks in C code to make sure we don't trigger bugs in older

- Added version checks in C code to make sure we don't trigger bugs in older
  SQLite versions.
- Added version checks in test suite so that we don't execute tests that we
  know will fail with older (buggy) SQLite versions.

Now, all tests should run against all SQLite versions from 3.0.8 until 3.3.6
(latest one now). The sqlite3 module can be built against all these SQLite
versions and the sqlite3 module does its best to not trigger bugs in SQLite,
but using SQLite 3.3.3 or later is recommended.