caput never uses ca_get_callback()

It would be nice to see the old and new element counts from an array field when putting a new array to it. Currently there is no way to ask caput to use ca_array_get_callback() to fetch those values so it can display the current array size instead of the maximum number of elements, it always displays the maximum number for the old and new values.

It's not obvious that the -c flag would be appropriate for turning that behavior on, given that we already use it to switch to using ca_put_callback(), which changes the semantics of the put operation.