Installing onto an already populated database wipes out all boards

[ghost]

Using the wizard to try to install FoolFuuka onto a database that already contains FoolFuuka data will wipe out a good portion of FoolFuuka tables (including all boards) and error out. Dropping all tables (or picking a different table prefix) seems to be the only way to successfully complete the wizard.

Ideally, the install wizard shouldn't trash any data. If it's unable to use an already existent schema, it should just say so and refuse to continue.