FEATURE: Allowing other methods to work alongside __invoke()

[b-hayes]

If the subject class implements __invoke all other methods are ignored.
It would be nice if invoke was only used if the first parameter doesn't match a class method, defaulting to invoke.
This goes against one of my main CLI scripting principles but would be handy in some cases.

eg.

//test command
public funciton _invoke()//returns "a default value"
public funciton alternate()//returns "something else"

and usage would be:

$ test
a default output value
$ test alternate
something else

and using --help would still list the other commands available while somehow indicating that the commands are now optional and something else will happen if no command is provided.