Simplified data mapper instantiation.
Code cleanup.
Fundamental reworking of the way functional tests are carried out:

- Full functional testing capability, using an SQLite database.
- No longer requires kludgy mocking of Doctrine object hierarchies.
- Includes a stronger Doctrine Mapper test suite relying on real data.
- Some test model tweaks to make testing easier.
- Some changes in other tests to reflect changes in method signatures.
Removed Doctrine ORM related mock classes.