added ability to specify a program load on the command line

CommandLine modified to interpret a single argument on the command
line as a program file name if it doesn't start with a '-'

if a program file name was specified on the command line, then it
overrides and saved program file (if the specified file does not
exists or has an error during loading, then the application starts
up blank, but with the program name set to the one specified)

the usage message was updated for the new command line argument