Add CArray.iteri

[Ant1-Provot]

Description

Hi !

Working with Ctypes I realized I needed a CArray.iteri method in order to iter over a carray passing the index to the argument function.

As it doesn't exist I felt it was time for me to do my first open source PR :)

Type of change

val iteri : (int -> 'a -> unit) -> 'a t -> unit

This is a new feature, non breaking that just adds a functionality.

How Has This Been Tested?

I tried to stick with testing and coding style of the already existing CArray.iterfunction:

• First test checks that the 3 loops of value + index indeed equals 9 -> 9 = (0 + 1 ) + (1 + 2 ) + (2 + 3)
• Second test checks with an empty list.

If you believe this change is futile for the code base

No worry, I just wanted to learn how to do an opensource PR.

[yallop]

Thank you for the contribution, @Ant1-Provot! This looks good to me.