Foreign key constraints support

[mrclmr]

Hey,

I was wondering if you have considered adding support for foreign key constraints. Enabling this feature would make it easier to handle cascading deletes and maintain data integrity within the SQLite database.

Thank you very much for your work and this excellent library.

[brendannee]

Great suggestion. I'll look into this. I think it might need to be optional, so that GTFS files with invalid entries can be supported.