introduce an add_python_targets command taking a list of python scripts and generating a target for each - a base tag is added to make the targets unique even if the filename is identical, i.e., for adding __init__ is different directories. The script copies the script to the build dir

also make sure that the path to generated to fixed in the generated __init__.py file

scripts to dune/alugrid

the model - will be removed later

all generated classes and to the MCMGMapper