Bcmxcp

Taking all defined meters in http://old.networkupstools.org/protocols/eaton/XCP_Meter_Map_021309.pdf and define constants for them. Comment for each meter constants if it has been mapped to a nut entity.
Add a number of meter map to nut entity mappings.
Improve handling of command return status, and replace magic numbers with constants in doing so.
Improve hadling of ups.load.
Add handling of topology block to set ups.description.
I have tested on PW5110, but it does not support most of the new meters mapped.
I do not have hardware to test the newly mapped nut entity mappings, and have asked the nut dev mailing list if someone with hardware other than PW5110 can assist in testing it.