small tweaks and improved consistency for Install.py in lib/kim

pgroup = parser.add_mutually_exclusive_group()

pgroup.add_argument("-b", "--build", action="store_true",

                    help="download and build base KIM API library with example Models.")

pgroup.add_argument("-n", "--nochange", action="store_true",

                    help="no changes to the base KIM API. Use currently configured one. ")

pgroup.add_argument("-n", "--nobuild", action="store_true",

                    help="use the previously downloaded and compiled base KIM API.")

pgroup.add_argument("-p", "--path",

                    help="specify location of KIM API installation.")

                    help="specify location of existing KIM API installation.")

parser.add_argument("-v", "--version", default=version,

                    help="set version of KIM API library to download and build (default: %s)" % version)

parser.add_argument("-a", "--add",

args = parser.parse_args()

# print help message and exit, if neither build nor path options are given

if args.build == False and not args.path and args.nochange == False:

if args.build == False and not args.path and args.nobuild == False:

  parser.print_help()

  sys.exit(help)

verboseflag = args.verbose

if pathflag:

  buildflag = False

  kimdir = args.path

  if not os.path.isdir(kimdir): sys.exit("KIM API path %s does not exist" % kimdir)

  kimdir = fullpath(kimdir)

  print("Created %s/Makefile.KIM_DIR\n  using %s" % (thisdir,kimdir))

else:

  kimdir = os.path.join(os.path.abspath(thisdir), "installed-" + version)

  if args.nobuild and not os.path.isdir(kimdir):

    sys.exit("Cannot use -n/--nobuild without first building the KIM API with -b")

# download KIM tarball, unpack, build KIM

if buildflag: