random() : var
Returns a random number uniformly distributed in the range from -1.0
to +1.0 (borders not included).
Uses the Lehmer algorithm with a period of 2,147,483,646.
random(var Max) : var
Returns a random number uniformly distributed from 0 up to, but
not including Max.
Initiates a fixed random number sequence, dependent on the "seed" s.
if(random() > 0) ... // true in 50% of all cases
abs, sign, randomize,