Test all elements of a list if they are numeric, positive numbers, integers or proportions (range 0-1).
testNumerics(numbers, positives = NULL, integers = NULL,
proportions = NULL)
[list] whose elements are tested for being numeric.
[list] whose elements are tested for being positive numbers.
[list] whose elements are tested for being integers.
[list] whose elements are tested for being proportions. between 0 and 1.