atest - copy argparse/test dir
changes to run tests with argcoffee allinone
allinone - default argcoffee

conflict_handler - partial fix (conflictHandler v _handler)
prefixChars/_chars
all tests now run

some changes in the test files to account for changes in argcoffee
i.e. change in case, uses of ArgumentError, use of underscore v camelcase

changes in allinone:
   correction in how options are pass to m-exclusive-group