Introducing: the Multi-user FetchMeister

- Now multiple things may use the same FetchMeister and share the throttling.
- Also as a side-effect, persisting FetchMeister-dependent ScheduledTasks for multiple runs should no longer end in disaster.
Fix/improve status reporting
FilmsUpdater now uses async parsing
New SWEBLE parser each time!

It has some sort of state that causes it to randomly break otherwise...
Catch and log common film extraction errors
Make an attempt to handle HTTP failures nicely
Extract more external ID for films
Handle redirects (in the FetchMeister)