Suggestion: More comprehensible Grid+ fan control

[dierks-m]

One thing I found to be a bit irritating was that the fans first kick on at 33% speed. Looking at the code, Grid+ doesn't accept anything below 4 volts - my suggestion is to spread the percentage range from 4 to 12 volts into 16 steps, being 6.25% accordingly.

Changes would apply to grid.py and also need the math module.

def calculate_voltage(percent): return 0 if percent == 0 else 3.5+math.floor( percent/6.25+1 )*0.5