Adding localized orbital scaling correction scheme

[mtesseracted]

I'm a grad student working on a DFA energy correction that relies on a modified version of MLWFs to obtain an energy correction. Here's the arxiv paper for the molecular version that uses a modified Foster-Boys localization scheme. I'm reaching out to see if once we've published our results for periodic systems if the maintainers would be interested in incorporating this new localization scheme in wannier90. The way it's currently implemented is I have a keyword parameter for the seedname.win file that triggers the new localization to turn on, otherwise it just does the normal MLWF. I would of course abide by the contributor rules and add testing for this functionality.