Revert to original names of reference classes.

The revision is not yet complete.  This version will install and a simple test like
```s
library(Matrix)
library(lme4)
Zt <- rBind(fac2sparse(Pastes$sample), Matrix::fac2sparse(Pastes$batch))
Lambdat <- sparseMatrix(i=1:40,j=1:40,x=rep.int(1,40))
Lind <- c(rep.int(1L,30),rep.int(2L,10))
theta <- rep.int(1,2)
X <- array(1,c(60L,1L))
tt <- merPredD(Zt = Zt, Lambdat = Lambdat, Lind = Lind, theta = theta, X = X, n = nrow(X))
tt$ldL2()
```
runs but there is still a lot of conversion to be done.