Initial version
Fixed up dropping of unused levels in grouping factors and expanded the README.
Added a demo and some methods for the LMMsimple type.
Create abstract model classes
Preparations for a formula/data interface.

Also need to create a version to split the Cholesky factor, as shown by large example.
First attempt at simple linear mixed models with Zt and X split (still not working)
Tighten up the deviance code for LMMsimple.

Also a bit of progress on the LMMsplit code.
Change the imports style.
Generalize some of the multiplication by RSC objects.
Got the LMMsplit deviance function working

There is now a lot of duplication between LMMsimple and LMMsplit.  The
purpose of having both is to allow for timing comparisons.  It may
well turn out that LMMsimple by itself is adequate.
Consolidation.  Split some functionality from LMM.jl to formula.jl
Factor the code; create abstract types LinearMixedModel and SimpleLinearMixedModel
rename
Create an abstract type linearmixedmodel and move some methods there.
Fix up lhs for terms like (1|Subject) for a non-simple model.
Rearrange file names
More work on the VectorLMM1 and ScalarLMMnest types
Got VectorLMM1 working to the point where betahat is properly calculated.
Finished VectorLMM1
VectorLMM1 using dense matrix methods when possible.