print statement deprecated
cbind added to model frame manipulation functions
%...in% functions added
order_by_name added
col_groups_name added
empty column groups not catted
as.data.frame.model.frame debugged
model_frame => as.model_frame
call to as.model_frame_basic deprecated
fitted frames thought about more carefully
as.fitted_frame added
apply_model will be re-thought using this framework