Error: fixed example usage for 'caller' attribute
Logger: close #132; switch from Moo to Perl OO

- Switching from Moo to Perl OO so the `Logger` object can pass back a
  `Log::Log4perl` object, instead of passing back a reference to
  itself
- Added checking for required argument `config` in `new()` method
idGamesDB: revert check for DB error in add_file()
db_tool/idgames_db_dump; issue #132; convert to use Logger module