Timing out due to incomplete fitting

[MJCliffe]

With occasional pressure datasets pascalapp.co.uk times out during the fitting as it requires too many iterations. This prevents everything from showing.

[ml-evs]

This is an azure app service startup config thing (see the gunicorn command at https://learn.microsoft.com/en-us/azure/app-service/configure-language-python#container-characteristics), though perhaps pascal should just fail for anything longer than the 10 minute default timeout.

[MJCliffe]

Underlying issue is that the scipy fitting function timeouts if it is slow to converge rather than terminating with a partial fit. I should probably get a better exception or be cleverer.