Various changes to /u
Various changes to /u

- Fixed a crash when urban dictionary does not return a valid reply.
- Fixed a crash when broadcast in PMs.
- Cache definitions to hopefully help with failed lookups.

panpawn/Gold-Server,panpawn/Pokemon-Showdown,Git-Worm/City-PS,panpawn/Pokemon-Showdown,Git-Worm/City-PS,panpawn/Gold-Server,panpawn/Gold-Server