fix using a Class for grouping commands --self shows as a flag

[devcydo]

Hi!

Fix issue #382

After a lot of research I found out that the only way (I'm 99% sure about this) of knowing if a function belongs to a class is using __qualname__. The only issue I see with this solution is that __qualname__ belongs to python 3.3 and newer versions.

Another solution that I can think of is to check and to remove the 'self' argument from every function, regardless of whether it belongs to a class or not. This solution will limit the user to not name the argument from a function, that doesn't belong to a class, 'self'.

Let me know what you think and I'll be happy to make the changes, as well as to make any correction :)

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