Parses the command line arguments

def parse_cl_args(arg_vector):
  '''Parses the command line arguments'''
  parser = argparse.ArgumentParser(description='Compiles markdown files into html files for remark.js')
  parser.add_argument('source', metavar='source', help='the source to compile. If a directory is provided, all markdown files in that directory are compiled. Output is saved in the current working directory under a md2remark_build subdirectory.')

  return parser.parse_args(arg_vector)