Preprocessing parameters

[guynir42]

Right now some preprocessing parameters are loaded from the instrument, and then overriden by kwargs to the run() function.

I think it is very unlikely that we will run multiple instruments' images using the same config file, so it would be simpler to just put all the parameters (e.g., which preprocessing steps need to be done) into the config, load them as critical parameters, and then have that be the only point of configuration for the preprocessing.

[guynir42]

Related to #104 and #173

[guynir42]

The way it works right now makes it impossible to figure out the provenances before actually running the preprocessing. This needs to fixed. I am putting in a hack that assumes we are using all the preprocessing steps but it needs to go into the parameters of the preprocessor object.

[guynir42]

Should also have a skip for filters parameter that lets you do stuff like "for g filter don't use defringe"

[guynir42]

Addressed by #305