Add native "round()" command

[GWRon]

We have floor() and ceil() to round integers downwards (to negative infinity) or upwards (to positive infinity).

ceil(0.6) = 1
floor(0.6 = 0

ceil(-1.1) = -1
floor(-1.1) = -2

Often we use this here: value = int(floatValue + 0.5) to avoid stuff like casting 3.0:float to integer (which can mean int(2.9999997) or int(3.000001)).

To avoid this issue we should compare the sgn() of the value ... or written differently:

if floatValue < 0
  value = int(floatValue - 0.5)
else
  value = int(floatValue + 0.5)
endif

or maybe it could be written this way:

value = int(floatValue + 0.5 - (floatValue < 0))

I think it would be good to have a native round() command which does a similar thing for the developer (in C we can of course write it ... shorter).

Having a round() command at hand might avoid issues as most people will most likely have used the old intValue = int(floatValue + 0.5)