r.squaredGLMM.mer(Mod) throws error if contrasts that have been used for random factors 
	in the "merMod" model do not match the ones in model matrix. This happens if
	there are factors in random part of the model formula and user has changed 
	relevant 'options(contrasts)' since the model was fitted.

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/mumin@269 edb9625f-4e0d-4859-8d74-9fd3b1da38cb