New Filter Options for Swordsmith Index

Swordsmith Index now allows filtering by Province and Era.

Note: when filtering by Era, only traditional Nengō are available. It's currently not possible to filter by historical periods (e.g. Nanbokucho) or sword periods (Koto, Shinto etc). This is due to the fact that filtering works off the specified Start Era field in the smith record. Therefore filtering by Koto period will only show records with Start Era = Koto, and not any Koto smiths as one would expect.