Context for lda-user-seed branch

[diazrenata]

I just made a branch with a new function that is a duplicate of LDA_set except, instead of nseeds, it allows the user to specify a single seed to use to run the LDA(s) (c3121c49395076075059e8c2dc85e18dfd2a1a5c). I don't think this will be something to incorporate into master, but it's helpful for me right now so I can rapidly explore cross-validation approaches using drake.