- regIOobject: don't re-register an unregister object on rename/assignment
- Hasher: split-off HasherInt with uint32_t specializations
- IOobject: writeBanner/writeDivider return Stream for easier chaining.

... also dropped some namespace bracketing while I was at it.

- 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

- The capitalization is consistent with most other template classes, but
  more importantly frees up xfer() for use as method name without needing
  special treatment to avoid ambiguities.

  It seems reasonable to have different names for transfer(...) and xfer()
  methods, since the transfer is occuring in different directions.
  The xfer() method can thus replace the recently introduced zero-parameter
  transfer() methods.
  Other name candidates (eg, yield, release, etc.) were deemed too abstract.

- drop copy components constructors in favour of the xfer versions. Even if
  the caller sends through constant data, if will be automatically promoted
  to xfer (via a copy operation).

- use xfer form for calls to resetPrimitives