bcmxcp: Add constants for all bcmxmp meter map, and replace magic numbers with constants

Take all the bcmxcp meter map defined in http://old.networkupstools.org/protocols/eaton/XCP_Meter_Map_021309.pdf
and put them into the bcmxcp.h file.
Update the bcmxcp.c file, replacing magic numbers for meter map by using the corresponding defined constant.
bcmxcp: Comment which meter map constants are mapped to nut variables
bcmxcp: map ups.date and ups.time to meters.

Not testes on hardware, due to lack of hardware supporting it
bcpmxp: Add mapping for output.L<phase>.power.percent to meters

Not tested on hardware, due to lack of hardware supporting it
bcpmxp: Add mapping for output.powerfactor and input.powerfactor to meters

input.powerfactor is not listed in http://www.networkupstools.org/docs/developer-guide.chunked/apas01.html,
so a bit unsure if this should be added.
Not tested on hardware, due to lack of hardware supporting it
bcpmxp: Add mapping for input.power to meters

input.power is not listed in http://www.networkupstools.org/docs/developer-guide.chunked/apas01.html,
but other drivers use it.
Not tested on hardware, due to lack of hardware supporting it
bcpmxp: Add mapping for ambient.1.temperature to meters

Not tested on hardware, due to lack of hardware supporting it
bcpmxp: Add mapping for input.realpower to meters

input.realpower is not listed in http://www.networkupstools.org/docs/developer-guide.chunked/apas01.html,
but other drivers use it.
Not tested on hardware, due to lack of hardware supporting it
bcpmxp: Add mapping for battery.current.total to meters

Not tested on hardware, due to lack of hardware supporting it
bcpmxp: Add mapping for output.L<phase>.power to meters

Not tested on hardware, due to lack of hardware supporting it
bcmxcp: Add handling of BCMXCP_RETURN_ACCEPTED_PARAMETER_ADJUST and others in ACK block

Add support for handling more return statuses when exeucting commands, the most important
being BCMXCP_RETURN_ACCEPTED_PARAMETER_ADJUST, which means the command was executed.
The others added all handles cases where command was not executed, but you now get a
more detailed entry in log as to why it was not executed.
bcmxcp: Use defined constants in setvar, and handle BCMXCP_RETURN_ACCEPTED_PARAMETER_ADJUST

Use the defined constants from header file, instead of magic numbers in setvar method.
Add handling of BCMXCP_RETURN_ACCEPTED_PARAMETER_ADJUST.
Report upsdrv_comm_good on successful execution of setvar to UPS.
bcmxcmp: Only calculate ups.load if the UPS does not report it directly

If the UPS does not report a meter mapped to ups.load, we try to calculate the ups.load,
but we do not calculate it if the UPS can report the ups.load directly
bcmxcp: Add Alf Høgemark as one of the authors for the driver