TODO list for MuMIn package:

*   model.names: return a textual representation of the model
*   model.avg: checking for consistency of contrasts used in the models
**  handling random effects in 'dredge' (in lme and lmer). Currently 'varying' 
        may be used with lme for that purpose
**  add a 'keep' argument for 'dredge' to return (a subset of) models (similarly
        as in 'model.avg' attr(*, 'modelList'))
       
