Discuss naming of FlavorTransformations

[JostMigenda]

• I’d like to rename MSWEffect, since that name sounds so generic that novice users would likely expect that to be the basic MSW case. Something like CustomMSW or AdvancedMSW would be clearer (and more consistent with AdiabaticMSW, NonAdiabaticMSW and their four-flavour equivalents, which all drop the “Effect” from the class name).

I agree, CustomMSW would be better here.
I kept all the class names initially defined by Jim in his branch, and didn't change anything because I'm not sure I have enough understanding of underlying physics 😃
But it will be good if we can come with a more clear naming convention in a discussion.

But probably we should do the renaming in a separate PR, it will be rather straightforward.

From discussion with @Sheshuk in #351 (comment)