DOC: Updated input methods doxygen

Reordered protected methods in ProcessObject header into 3 groups,
Input, Output, and Pipeline methods.

Change-Id: I220f26086a3a065e1f235a060987931fde825b78
ENH: Use named inputs in BinaryReconstruction filters.

The named input ProcessObject functionality is put to use for the MarkerImage
and MaskImage in a backwards compatible way.

Change-Id: I06afdea17381b49abcc4d8be1183e42cae866558
Merge topic 'NamedInputsCompatibility'

6ac3fcd ENH: Use named inputs in BinaryReconstruction filters.
e94e30f DOC: Updated input methods doxygen