cleaned up and clarified usage
add -h|--help
-must specify -g or -s
-check arguments and give appropriate errors
-pull get/set to separate subroutines
fail when extra arguments are present
made usage clearer by putting valid values in the arg list
re-ordered methods
updated some comments
indent arg descriptions
enumerate methods to not retype strings all over the place
abbreviate methods and add synonyms
trailing whitespace
append usage to README
update copyright