ENH: add '_bytes()' versions of List data(), cdata()

- simply adds in the reinterpret_cast, which simplifies coding for
  binary data movement.
  Name complements the size_bytes() method for contiguous data

STYLE: container IO.C files into main headers for better visibility

STYLE: include CompactListList.H in polyTopoChange

- avoids future mismatches if the CompactListList template signature
  changes

GIT: relocate CompactListList into CompactLists/ directory