If model failed to recompute with some parameter value, paraseries
failed altogether due to a coding error in console log message.
Fixed. Now, the behavior that was intended from the beginning is
observed: the shape that failed to be produced is replaced with a fail
marker, and the error is just logged to console.
If recomputing a paraseries, enable recomputing of nested paraseries
automatically. So that deeper paraseries may remain switched off, but
becoming active when top-level paraseries is recomputing.
Clicking property editor while the feature is recomputing was causing a
crash. Explicitly showing progress will stop the clicks reaching
property editor (because dialog is modal), and, hopefully, will prevent
crashes.
