Replace '_' with '-' in command line option flags

Generate more beutiful command lines by not requiring the user to enter
the under natural '_' for command line options where '-' would usually
be expted. For example "--my_opt" is not generated as "--my-opt". Closes
issue #37.

CHANGELOG

@@ -7,6 +7,7 @@ Next release 0.8
 * Create positional command line arguments for require parameters
 * Published Python wheel packages to PyPI to improve install times
 * Custom help formatters for control command line help output
+* Replace '_' with '-' in command line option flags
 * Deprecate context.return_value for context.last_return and
   context.return_values
 

begin/cmdline.py

@@ -115,7 +115,7 @@ def populate_parser(parser, defaults, funcsig, short_args, lexical_order):
             if kwargs['default'] is NODEFAULT:
                 args.append(param.name)
             else:
-                args.append('--' + param.name)
+                args.append('--' + param.name.replace('_', '-'))
                 if short_args:
                     args.append('-' + param.name[0])
                 if 'help' not in kwargs: