Streamline PGLS code, pave way for alternative models.
Add the code needed for the PGLS-via-pruning to work.
Simplify MCMC subsetting.
Added Sachs 2013
Mercurial ignore file definitely not needed any more!
Simplify EB code, using the *other* tree rescaling code.
Univariate lambda model (vcv and pruning [C and R] supported).

Contrasts not done yet.