The patch-specific mapper interfaces, fvPatchFieldMapper and
pointPatchFieldMapper, have been removed as they did not do anything.
Patch mapping constructors and functions now take a basic fieldMapper
reference.
An fvPatchFieldMapper.H header has been provided to aid backwards
compatability so that existing custom boundary conditions continue to
compile.
Specific names have been given for expand functions. Unused functions
have been removed, and functions only used locally have been removed
from the namespace. Documentation has been corrected. Default and
alternative value handling has been removed from code template
expansion.
