Full support for Power board r5B12

[prasimix]

Basic support that is added into M4 (e.g. support for 16-bit I/O expander, automatic selection between low and high current range) has to be extended to cover all aspects of this new board.

• Taking into account reference ground when displaying output voltage and current for remote voltage programming is activated (VOLT:PROG EXT). The same offset has to be used as for uncalibrated channel (we need this for r5B10 board too!)
• Support for two current range in calibation procedure. Use additional SCPI command e.g. CALibration:CURRent:RANGe HIGH|LOW for selecting range that will be calibrated. In calibration wizard high range current follows voltage calibration and low range follows after that. When switch from MAX value to low range MIN value, output current has to be set to 0 first.
• Add new feature with new SCPI command e.g. SENSe:CURRent[:DC]:RANGe:AUTO ON|OFF (default is OFF!). When monitored/measure current auto-ranging is switched on we have the following special case: If I_SET is higher then 500 mA and I_MON is less or equal to 500 mA (i.e. channel is in CV mode) then low range has to be selected on the I/O expander with "temporary" I_SET set to 500 mA. But, if current rise over 500 mA then high range has to be selected on I/O expander first and followinf by seting of initial I_SET value. For example, I_SET = 3 A, and U_SET = 3 V. With 10 Ohm load I_MON will be 300 mA. Therefore new (temporary) I_SET is MAX that will become 0.5 A when low range is selected. If load is changed or voltage is increased to e.g. 20 V we have to set back I_SET to 3 A (effectively that will limit voltage to 9 V with the same load and channel will enters CC mode). In this way we can insure the best possible current measurement. This operation makes sense only in CV mode!
• Emulate above mentioned behavior in Simulator

[prasimix]

All functionality tested except when channels are in tracking or coupled mode, since I don't have two r5B12 power boards currently on disposal. If anything arise with them in a future a new issue will be opened.