Overflow in calculation of axes range in partial dependence plot

[gkronber]

Models which produce a large range of outputs i.e. in the range 0 .. 10¹⁰ lead to an overflow in CalculateAxisInterval in particular in methods RoundDown() and RoundUp(). Both methods cast to an int which limits the maximum range to the 2³¹. The cast to integer is however not required as the code should be fine with floating point arithmetic.

[gkronber]

r17861: fixed overflow because of integer cast in ChartUtil