ENH: Subtle renovations in wall function documentation and input

  - Improves header file documentations
  - Adds const specifier to various objects
  - Allows various model constants to be user-defined
  - Changes from lookupOrDefault() to getOrDefault()
  - Consistent namespace usage:
    - If the WF belongs to only Foam:: namespace, use Foam:: explicitly
    - If the WF belongs to more than one namespaces, put the WF in namespace
      parentheses
  - Adds the missing dashes in comments required by Doxygen
  - Corrects capitalisation in comments
  - The terminology 'viscous sublayer' was preferred over 'laminar sublayer'
    due to the fact that the sublayer is not laminar.
  - The order of initialisation of fields is changed to be the same across all.