fvPatchFields: Constructors from dictionary now call the corresponding...

fvPatchFields: Constructors from dictionary now call the corresponding constructor of the fvPatchField base-class
to ensure 'patchType' is set as specified.

Required substantial change to the organization of the reading of the
'value' entry requiring careful testing and there may be some residual
issues remaining.  Please report any problems with the reading and
initialization of patch fields.

Resolves bug-report http://bugs.openfoam.org/view.php?id=2266