Memory bugs repaired in jw_ptv.c and multimed.c

quit_proc_c()  :On closing the program, not all the memory was returned
to the system.
init_mmLUT(): Memory was allocated each correspondences
cycle, but never returned.
New method of zooming: modified Tcl-files

Introduction of a nicer way of zooming and the use of scroll bars.
However, there are still some limitations, i.e. zooming >800% is not
possible.
New method of zooming, the modified C-files

Zooming should work now, but ....