Use managed algorithms again at the top level in Python.

This restores the progress reporting to the GUI as anything going through
the AlgorithmManager::create method is automatically tracked.
Refs #9203
Merge remote-tracking branch 'origin/bugfix/9203_script_alg_progress'
Refs #9007 Swap interface widgets to handle loading files.
Merge branch 'bugfix/9007_dataselector_commit_missed' into develop