Add niceNoDataValue

[jakimowb]

Add a function that creates a nice noDataValue for a given set of valid data values

The no-data value should be (i) out of min/max range, but (ii) still close to min/max range to ensure nice default color stretches for GUI that do not mask no-data values

[] -> 0
[None] -> 0
[1,2,3] -> 0
[0,1,2,3] -> 255
[-1,0,1,2] ->255
[0.23, -34] -> -99
[0.23, -343] -> -999