New stuff
- Arena IDs are now accessible from all `cards` objects with `arena_id()`.
- The `lang` attribute is now accessible from all `cards` objects with `lang()`
- `printed_name()`, `printed_type_line()`, `printed_text()` have been added to all `card`
objects.
- `lang` optional argument has now been added to `Collector()` object. Defaults to `en`
Changes
- Key errors are now handled more cleanly, and doesn't return two traceback errors.
- Updated sets to be more like the other classes in structure.
- Updated symbology to be more like the other classes in structure.