CFM: Deprecate complicated dofdex
@pfrank @jroth As discussed previously.
This change will help to maintain the correlated field model. Note that no functionality is lost. If users want to use nontrivial dofdexes, they can instantiate the CorrelatedFieldModel multiple times.
My plan is to remove this deprecation warning and the advanced dofdex features in approx 2 months (if noone objects).
Edited by Philipp Arras