Returns a non-reproducible random float in the interval [x,y[

Examples:

1) rand2f(0,1); Returns a non-reproducible random float between 0.0 and 1.0
2) rand2f(0,1,1,2,2,3); returns 3 non-reproducible random float
respectively between 0.0 and 1.0, between 1.0 and 2.0 and between 2.0 and 3.0