all the time, not just when there are connections. This is because we
need to be able to signal the caller via their destroy callback when the
view has died, whether or not there are connections. The alternative is
to force the caller to deal with at least two different ways in which the
view can disappear. Required adding code to deal with what happens when
there no views left but gtk is still calling this routine.

Add better routines for returning View status, needed by zmapControl.

zMapCreate() now only makes the topwindow, does not do the connect bit,
this must be a separate function applicable to a specific view within
the ZMap.
Add calls to add/connect/load/delete views.
Change logic to examine state of views before allowing operations on them.

and associated threads.

Calls window code with parent container widget to create data display
window. Maintains a list of windows as there may be more than one.

Handles list of connections via zmapconnection code.

Maintains state of a view and handles data loading/resetting etc.