ENH: enabling delegate option for SWIG in Python

Turning on the delegate feature for all languages, those which don't
support the feature should safely ignore it.

Adding Example for deriving a Python class from sitk::Command for
progress reporting.

Change-Id: Id923d5c5c67f5bb19cad0df9d33e09d4d9d32cca
Fixing CXX Progress example to match python.

Change-Id: I5d34289461614f85aa53d5e3820f8b39f21481bd
Merge topic 'SIMPLEITK-462_CommandClassAsSWIGDelegate' into next

ff574d0d Fixing CXX Progress example to match python.
25609124 ENH: enabling delegate option for SWIG in Python