- If you call `[db close]`, it should reset `isOpen` to false;
- When you try to use `[queue database]`, it should not only check that the `FMDatabase` is non-nil, but also whether the database is open or not;
- Added `testClose` test to `FMDatabaseQueue` logic if the queue's `FMDatabase` was closed.
- Add explicit exclusive transaction code
- Add warning to beginTransaction and inTransaction calls that while it's currently exclusive, we reserve the right to change this in the future
- Add a few tests while I was here
- Audited for nullability;
- Updated `makeFunctionNamed` and added associated utility `value` and `result` methods;
- Added URL methods;
- As adding tests for new methods, expanded test coverage a bit (now over 80% coverage);
- Updated VFS tests to make sure they unregister;
