mocha test for proper handling of '--'

originally they were all deleted
then a py patch deleted just the 1st - in each group of positionals
also address cases like '-a--'

http://bugs.python.org/issue14364
http://bugs.python.org/issue13922
change to parse '-ku' like '-k -u'

http://bugs.python.org/issue16142

dashku.js - is sample file, not unittest
parse_known_args - puts '-u' in extras instead of raising error
change in 'required' error messages

Was 'too few arguments'

Now 'the following argument(s) are required: (names)

subparser action now is 'required = true' default
   also has a custom getName() that returns choices if metavar or dest is  not defined.

changes in base.js, sub_commands.js to reflect error message change.

test_allinone1.js - tests for these changes
   similar to tests added to test_argparse.py for this issue.
   it also tests for scientific notation
   default_to_positional option