PamelaWare Database Upgrade Strategy

For all 2008 versions of PamelaWare, the following strategy is used to detect changes to the database:

1. Plugin code contains a database version variable: PW_DB_VERSION.
2. Database options contain a database version variable: pw_db_version.
3. When the mysql database version does not match the file database version, we either have a mismatch or an upgrade.

Note, this only works if we remember to increment the database version every time we make a change, and write upgrade code to be placed in PW_PLUGIN/db_upgrade.pw.php...