rename nu::stack to nu::Array

b/c it's an encapsulation of a stack array.
rm testing hack
do current sensor conversion for HAIS-50P

also propagate nu::Array renaming. (1/2)

Also extremely unsure of proper units for HAIS-50P. I tried to convert
from AD7685's output by dividing by 1E6.
update BMS code for HAIS-50P

propagate nu::Array renaming (2/2)
update CAN namespace structure & interface

added object-oriented TX & RX functions. added meaningful name to
nu::can::frame::Packet's union's struct.
organize BMS trip configuration, begin nu::Trip library