SwitchStateExt Message support

[ari2605]

• e2p_layout PowerSwitch.SupportedSwitches.MaxValue has to be increased
• maxVal in e2p_powerswitch_get_supportedswitches has to be adapted
• There is a new variable switch_count which holds the number of selected
  switches read from EEProm.
• In the current Implementation the Number can be Max. 6 since PORTC is used as Output and has only 6 Bits. To Discuss: what if more Pins required?
• If MessageID is not MESSAGEID_POWERSWITCH_SWITCHSTATE of MESSAGEID_POWERSWITCH_SWITCHSTATEEXT no Response is sent (as in the original Version).
• For Sending Status the switchstate_ext Message is used in case switch_count > 1 else switchstate Message is used.
• The Debug LED is currently driven by Relais0. - - - What shall drive the LED if switch_count > 1?
• At the Moment there is only one input read for Toggeling Relais[0]. Shall we read more input pins if switch_count > 1? How to configure? We have PIND3,4,5,6.

[breaker27]

I'll close this patch since basic support is implemented now. Max number of switches in e2p is updated. At the moment, support will be limited to 6 switches which I think is also enough (PINC0..PINC5). More LEDs and buttons have to be supported. I'll think about how to do this. I'll add a new issue for that.