- use first() method in some places as well where it helps clarity

- there are a few remaining cases: git grep 'size()-1]'

- this builds on Mattijs' commit 968f0bbd but with a first()
  as well.

- Added both to FixedList, IndirectList, UIndirectList and *PtrList and
  since they can certainly be useful there. Did not add to BiIndirectList,
  since I'm not sure what it should mean there. Did not add to PackedList,
  since it's not clear how useful they'd be yet in these contexts (and I'm
  not sure how it would interact with the iterator proxy implementation).

- Note: STL defines front() and back() for these methods.

This currently only runs in serial, parallelisation is worked on.

- mention PV3blockMeshReader in the README as well

models derived from Smagorinsky.

fvMotionSolver/pointPatchFields

Removed blank lines between template specification and function definition.

- added asText() method to assist people with remembering what the
  dimensions are in English

- minor short-circuit optimizations in dimensionless() and operator==