DBTool: issue #190; add new attribute 'filename' for database file

- `45-DBTool.t` test can now tell the _DBTool_ object what filename to
  use for the output file
- Added proper calls to the `$view` object for `request_success` and
  `request_failure` callbacks
Error: issue #192; change 'raw_error' to just 'raw'

- Document the defaults used for each attribute in the _Error_ object
Roles/Database: test for defined filename attribute in connect()
Roles/DatabaseSchema: issue #181; added more callbacks to DBTool

- Document what callbacks can be called in the `apply_schema()` method
- Don't use the short name `$cb` for callbacks, too easy to miss when
  scanning source code
idGamesDB: issue #192; change 'raw_error' to just 'raw'
45-DBTool.t: close #190; added temp output database file for testing

- Fixed check of callbacks in test, so when callbacks are called, the
  expected callback is shift()ed off of a list of expected callbacks
- Added a `request_success` callback for testing