Rather than overriding the default path to the PRISM source directory by
setting the PRISM_SRC_DIR environment variable, do so by supplying an
argument to the script.
Rename the following makefile variables for the sake of clarity in child
makefiles:
SRC_DIR -> PRISM_SRC_DIR
CLASSES_DIR -> PRISM_CLASSES_DIR
OBJ_DIR -> PRISM_OBJ_DIR
LIB_DIR -> PRISM_LIB_DIR
INCLUDE_DIR -> PRISM_INCLUDE_DIR
IMAGES_DIR -> PRISM_IMAGES_DIR
DTDS_DIR -> PRISM_DTDS_DIR
The helper script src/scripts/printversion.sh also makes use of the
value of SRC_DIR exported from the main makefile, so use PRISM_SRC_DIR
in that script too.
Chris Novakovic