Added progress dialog.

Problems with how ParaView fires progress now become obvious. We need to
cleanup ParaView's progress reporting infrastructure and this will start
working better.
Adding ModulePropertiesPanel.

Added properties panel for modules. This adds a mechanism for each
module to show relevant properties in the ModulePropertiesPanel.

Also added support for deleting modules.
Added ability to toggle module visibility.

PipelineWidget now has 2 columns, the new one is used for showing
eyeballs for visibility.