added common type for vars file options of list_input to Loci

[wandadars]

I've seen this list_input used in the vars file parsing and I thought maybe it would make sense to be part of Loci. I put it in the Loci_types.h, but if it makes more sense somewhere else, I can change it.

[wandadars]

The effect here is that dependent codes that have their own list_input implementations would have to remove theirs. They are commonly in the sciTypes.h or sciTypes_base.h files. And replace any instances of <code>::list_input types with Loci::list_input

[EdwardALuke]

I am wondering if we should change the name of this function. It doesn't really read a list, instead it reads a string up to the end-of-line. So the list_input is a bit of a misnomer. Alternatively, we could make this actually parse lists as comma separated lists and provide some infrastructure for multi-line inputs. But doing this might make interfacing with existing code a bit more involved depending on the details.

[wandadars]

I think I see what you're saying. Have it return an already parsed accessible list of the comma separated entries by default. Definitely a 4.2 update.