KNX : Improve handling of DPT 3.007

Data returned by 3Bit controllers on the KNX network consist of 2 parts. a Control bit and and 3-bit Stepcode field. The Calimero translator take the control bit as the primary Value when translating, this yields erratic behaviour on KNX controllers that send a value when a button is touched, and a second value when the button is released ("break" value). The Basalte Deseo controller for example sends 0x9 for a volume increase (Control 1 Step 1), and a 0x0 (Control 0, step 0) as break. Volume decrease is 0x1 (control 0, step 1), followed by a break. So, in order not to generate INCREASE + DECREASE when volume goes up, and DECREASE+DECREASE when volume goes down, we have to ignore the 3Bit values where step = 0