Add testing for implicit_values and non-consuming of separate tokens.

The testing did not really provide support for implicit_values or positional arguments.  So, I added this.

Instead of introducing a new character for the syntax and since ```?``` and ```=``` had the same meaning, I changed ```?``` to be used for implicit_values (as in regular expressions it is 0 or 1).  All previous uses of ```?``` were changed to ```=```.

To make sure that positional arguments were not being consumed, positional_object_description is set up only for implicit_values.  The test_cmd code also needed to be slightly modified so positional arguments were taken as part of the previous option as position != -1.

Feel free to change anything.