Shorten and standardise struct names

[seabbs]

As discussed in #496 many of the struct names are quite long and are not 100% consistent. We should enforce consistency and also aim for less verbose struct names.

I think an easy change is to go from

• Observation -> Obs

Any other suggestions?

To minimise breaking changes I think we should do a single renaming PR so lets collect suggestions here.

[SamuelBrand1]

Could we not do this with some alias names?

[SamuelBrand1]

e.g.

const NiceAlias = VerboseStructName

This is a cost free abstraction

[seabbs]

Yes we could and I agree that would be good for another issue (i.e add alieas for example making AutoRegressive exist and AR, RandomWalk and RW but the key issue we have here is making sure we have a standard and following it.

Thee big thing that stands out to me is the the module is called EpiObsModels and we have RecordExpectedObs but everything else uses Observations

[seabbs]

(could you make the alias issue :). )