- the bit counting is relatively fast:
  under 0.2 seconds for 1M bits counted 1000 times

- trim()'ing the final zero elements tested for a few cases,
  but might need more attention

- ditched PrimitivePatchExtra in favour of a PatchTools class that is
  currently just a collection of static functions. They could equally well
  live within PrimitivePatch itself, but isolated also has its advantages.

- MeshedSurface, UnsortedMeshedSurface now have 'regions' instead of
  'patches' since they are more like a faceZone for meshed surfaces than
  patches. This might avoid confusion at a later stage.

- can use the same syntax for boolList, PackedBoolList and labelHashSet
    if (myHashedSet[x]) ...
    if (myBoolList[x]) ...
    if (myPackedList[x]) ...

- exists() = forward to OSspecific exists(...)
- isDir()  = forward to OSspecific dir(...)
- isFile() = forward to OSspecific file(...)
- IOobjectComponents() - split into instance, local, name following rules
  set out for IOobject.

- added IOobject(path, registry, ...) constructor that uses
  fileName::IOobjectComponents(). This hides the complexity we otherwise need.

- set() handles overflow as max_value() - the principle of least surprise.
- use pointers in iterator to avoid any assignment issues. Allows default
  bitwise copy/assignment.

- added Mattijs' speed tests
- optimized resize() and assignment operators to avoid set() method
- add const_iterator and re-did the proxy handling.

Reading/writing by looping across iterators is still somewhat slow, but
might be acceptable.

largest and smallest representable values.  Accessible directly and via pTraits.

- eliminated previous PackedBitRef class, the iterator does all of that and
  can also be used to (forward) traverse the list
- no const_iterator yet

- Note that PackedList is also a bit like DynamicList in terms of storage
  management and the append() method. Since the underlying storage in
  integer, any auto-vivified elements will also flood-fill the gaps with
  zero.

- removed Cmu from kOmegaSST models - not used
- general tidying up

- new members:  capacity(), two-argument resize()/setSize(), const storage()
- new static members: max_value(), packing(), etc.