dump_idgames: updated usage example
Roles/Database: add support for temp databases

- A `temp` database is one that is created using a temporary filename,
  because no filename was specified in the data base connection string
- Updated all methods to return a value of some kind, either `1` for
  success, or an `App::WADTools::Error` object if there was an error
40-idGamesDB.t: added test of `get_file_by_id`/`get_file_by_path`

- Added a bunch of test file IDs and paths
- Check all database calls for an Error object being returned
- Comment out test plan and use `done_testing()` to show when testing
  is completed