Handle call functions like properties

[JensOgorek]

This should handle calls like functions in the background.
For example, x.mute() should be x.mute = true as a property in the background. This will be useful to handle function calls in startup scripts for expander ESPs, since they now can be handled like properties do with #91

This is for all function calls, that could be properties.

[JensOgorek]

This is closed with #117, we chose a different approach.