No way to specify delay model with opt_main

The delay estimator is used in one pass in the optimization pipeline (bdd cse which replaces expressions with simpler equivalents). There is no way to specify the delay model in opt_main so the default delay model is always used. We should have a way of specifying it or replace the use of the delay model in that pass.

Start at the opt_main entry point and trace the optimization pipeline, especially the bdd cse pass where the delay estimator is used. Determine whether the intended change is to let opt_main select a delay model or to remove that pass's dependency on the model. Done means the chosen behavior no longer always uses the default delay model.

Written by the indexing model from the issue text.