remove min and max function.

Use standard  minElement and maxElement functions

If I try to use `maximum` with object that  isn't Comparable it will crash at runtime. There is no type checking
`var maximum : Int = [A(), A()].maximum()` - Crash
`var minimum : Int = minElement([A(), A()])` - compile error
`var minimum : Int = minElement([1,2,3,4,5]` - work perfect 

I was trying to wrap minElement inside minimum. I failed because arrays don't have to store Comparable elements.
I suggest to got for standard `minElement` and `manElement`