pointsInstance.

For now also dump topology related sets to pointsInstance since otherwise
paraFoam cannot see them (only looks at first 'sets' directory when searching
back)

- can use 'XX.empty()' instead of 'XX.size() == 0', 'XX.size() < 1' or
  'XX.size() <= 0' or for simpler coding.
  It also has the same number of characters as '!XX.size()' and /might/ be
  more readable

- many size checking had 'XX.size() > 0', 'XX.size() != 0', or 'XX.size() >= 1'
  when a simple 'XX.size()' suffices

- boundBox::invertedBox is useful for initializing our own calculations
- NOTE treeBoundBox::greatBox is still in place, since it uses GREAT
  instead of VGREAT. If this is only historical, we can drop it.