Add variables for voltage, current, frequency, power factor sector and support for 3-phase systems to S-POWER Type

[Redguy]

I an currently implementing a My Sensors imlementation that reads measurements from a Schneider PM9C Energy monitoring device through Modbus and feeds those measurements into the MySensors network.. This is quite a nice device to use but a lot of measurement have not been implemented in the sensor types provided in the MySensors library.

The S-POWER type (type 13), meant to be used for this kind of devices only supports the V_WATT, V_KWH, V_VAR, V_VA, V_POWER_FACTOR variables. I can add the measured Voltages and Currents by using the S_MULTIMETER type, but still. I think many power meters out there support a lot more then just the pure power readings.

The PM9C for instance provides me with :

• Current measurements for each Phase and the Neutral line
• Voltage measurement between the 3 Phases and for each Phase against Neutral
• Frequency
• Total and per Phase Active power
• Total and per Phase Reactive power
• Total Apparent power
• Power factor
• Power factor sector
• Power demand
• Maximum power demand
• Operating time counter
• Active and Reactive total energy counter

Sure i can use custom values for this, but it would mean defining 3 devices types for this one powermeter.

I suggest adding the existing V_VOLTAGE, V_CURRENT variables to the S-POWERMETER type, and add new variable types for V_FREQUENCY, V_POWER_FACTOR_SECTOR, V_POWER_DEMAND