Document LinearFold+mfe and make linters work

[Koeng101]

I merged much of linearfold directly from https://github.com/allyourbasepair/rbscalculator - and so, not only are the linters very unhappy, but there are lots of missing spots for better documentation (though vivek did very well in most of the code).

I am putting a documentation issue here: squash all linter bugs, add documentation and context for everything in the LinearFold+mfe packages, and generally clean it up to be up-to-spec with the rest of the project.

I am adding it now because I believe we need to get it into the tree, then can begin improvements in an iterative process.