Comulative density function interface

Example

import std.traits, std.mathspecial;

class NormalCDF : CDF!real
{
	real opCall(real x)
	{
		return normalDistribution(x);
	}
}

auto cdf = new NormalCDF;
auto x = cdf(0.1);
assert(isNormal(x));

Example

CDF!double cdf = GammaSCDF!double(1, 3).toCDF;