Fixed
- `merge_cards` and `merge_notes` didn't update metadata of return value, resulting in errors like
`Unknown value of _df_format`. Issue 42
- `force` values weren't passed on, resulting in AnkiPandas refusing to do anything
when writing out
- On Windows the int size is 32 bit even on 64 bit computers, resulting in issues with
large values of ids. Issue 41