vc.icn: Program to coordinate visualization programs

This program loads and runs multiple MPs.  It is based on the original
visualization coordinator, Eve, written by Clint Jeffery.

This is a work in progress.  At the moment, it works in demonstration
mode with only hard-coded SPs and MPs available.

The following interface features are provided:

     File menu

        snapshot @S     take snapshot of selected visualization
        quit     @Q     exit from vc

     Pause toggle (@P) to stop and start visualization

     Speed control slider for SP events

     Display of clock ticks in SP
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The following features remain to be implemented:

   disabling and enabling MPs
   adding and removing MPs
   specification of SPs and MPs not in hard-coded list
   specification of input data for SPs
   attempt to position MP windows in a useful way
   provide for changing SPs
   provide for continued visualization when SP terminates

Also, there are numerous small problems that need to be fixed, as
well as better documentation.