Some scripts/C/Java for the Raspberry Pi server.

powermng.c manages power for the RPi based on battery SoC and grid state,
eg dumping some excess power to a load taken from grid at optimal times.

Some key updates:

2016/09/25: B1 temperature logging and compensation.
2016/09/24: created BATT1_MINUSAGE_mV_per_day; tiered 'e' dump triggers by days.
2016/09/17: attempt to suppress dump oscillation with tweaked thresholds.
2016/09/11: commented out most of B2 (Li) code.
2016/09/11: dump margin and sag calcs now dynamic with load compensation.
2016/09/10: more cautious after reboot in reliance on last-VHIGH flag timing.
2016/09/10: added live calc of implied supply impedance to RPi.
2016/09/09: made time since VHIGH determinant of less aggressive dumping.
2016/09/07: prioritised dump load triggers further.
2016/09/01: dumping less aggressive if battery not FULL for several days.
2016/09/01: moving locking to mbacess to be shared by the command-line tools.
2016/08/30: encouraging dump is battery > 'medium' and grid not 'green'.
2016/08/28: added FULL state (>=VH and battery in float) and flags.
2016/08/25: split out separate mbaccess.cpp wrapper.