catalyst: Remove hard-coded writers

Instead, use allow any writer to be specified.
catalyst: Update example scripts
catalyst: Add writers for the various explorers
catalyst: Support older ParaView versions

The data_exploration module is not always available, so support it
missing (specifically, ParaView 4.0.1).
catalyst: Remove default'd parameter

It has a default value now, but older versions don't have the parameter
at all, so support both.