Document and rearrange order of initializing members of plPlotterPtr
and plFramePtr structures in same order as the members of the
structures are defined to help keep track of what is initialized and
what not. There is no change in initialization of plFramePtr, but
this analysis showed that both plPlotterPtr->double_buffer and
plPlotterPtr->pldis (and several other members which were also not
initialized in the working plFramePtr case) were unitialized. The
double_buffer initialization quiets a valgrind warning about an
uninitialized variable. The pldis initialization may not be necessary
(because valgrind did not complain about it), but it does follow what
is done in the plFramePtr case.
These plPlotterPtr initialization changes made no difference to the
erratic on-again off-again issue with test_wish_runAllDemos where
sometimes the examples run at the touch of the button consistently for
one particular compilation of plplotter.c, and other times they error
out consistently for a different compilation of plplotter.c with
invalid command name "x00"
So it appears some other issue is the source of the complete change in
behaviour of the plplotter Tcl/Tk extension package from one
compilation of plplotter.c to the next.