Fixed recent file menu for data sources/state files.

Updating recent files menu to work with TEM state files and data
sources.

Also fixed LoadDataReaction to prompt for reader properties (needed for
raw files).
Working on cleanin up Python operators.

1. Update API to work with ParaView/VTK master.
2. Added placeholders to locate Python module paths.
3. Update how operator script is executed for better error reporting.
Merge branch 'operators'

* operators:
  Working on cleanin up Python operators.
  Fixed recent file menu for data sources/state files.