- evaluate()
  the communication type is exposed as a parameter to allow for more
  tuning, but default parameter remains defaultCommsType so there is
  no change in behaviour for existing code

- evaluate_if()
  supports a general selection predicate

- evaluateSelected()
  now does initEvaluate() for all patches, waits and then calls
  evaluate(). This avoids potential deadlocks when multiple patches
  are inter-communicating.

ENH: align DimensionedField reading with GeometricField treatment

- use localIOdictionary to obtain the dictionary contents

ENH: update GeometricField code

- change GeometricField writeData() as primary output method
  (not operator<<) for better clarity of purpose

- use unique_ptr for GeometricField demand-driven data