delete a logical signal
int dellosig(ptfig, index)
Pointer to the figure in which the signal should be deleted
Index of the signal to be deleted.
dellosig delete the signal that has index as INDEX
in the figure pointed to by ptfig.
The list consistency is maintainded, and the space freed.
dellosig returns 1 if the signal has been deleted, 0
if the signal index does not exists in the list.
char *was_existing(ptfig, index)
return dellosig(ptfig, index) ? "you just killed it!"
: "wasn't here anyway";