Module containing relational operators.
Author: Rudla Kudla
Version: 1.0
Test whether x is bigger than min and lower than max.
If the x is lower or equal to min, max is not evaluated.
min < x and x < max
Test whether x is bigger or equal to min and lower or equal to max.
If the x is lower or equal to min, max is not evaluated.
min < x and x < max