increment the parse_ variable on unnamed subcommands.
update the readme, and add a formatter test for nameless subcommands in nondefault group with other named subcommands.
add a test of default arguments
add a formatter test
add tests for unnamed subcommands and an example of the partitioned subcommands.
change the app_p to be a shared_ptr so you can add an App later on and merge them together
add the ability to add unnamed subcommands that allow partitioning on options into multiple apps.
