Clean up ChapelRange for c for loops

This is some cleanup and old code removal for c for loops.

It removes is isMaximal check as it is wrong (and has been wrong for some
time.) This only handles the case where we have a non-strided range because for
some reason we only set the stride after range creation by calling a "by"
method on the range so we don't actually know the stride and constructor time
which seems like a problem. I ran into this when I was adding and testing the
wihtinBounds function, which was intended to replace maximal range
checks/warnings but I ran into the same problem. Currently we could move this
into the these iterators, but that's not ideal as you have to add it to every
bounded range. I would like to just let maximal range tests regress for now and
don't put c for loops on hold to fix whatever is going on.

Other than that, this just cleans up the c for loop iterator and adds some
comments.