ENH: refine handling of DynamicList/DynamicField resizing

- previously had special resizing treatment for the corner case when
  the addressable size and the new capacity are identical. However,
  that particular approach (to minimize copying) meant that the exact
  deallocation size would likely be incorrect.
  Having the correct deallocation size becomes more important with
  alternative allocators.

  Introduce resize_copy() protected function to limit the number
  of elements copied during the resize.

ENH: provide DynamicList/DynamicField constructor with sizing

- allows fine-grained creation of a DynamicList/DynamicField with a
  given size/capacity without an initial value.

COMP: typo in code for DynamicList::push_back() with IndirectList