turbulence models get thermal dissipation source term(s)

- thermalDissipation()
  corresponds to the energy lost due to viscous efffects and
  what exits the energy cascade via dissipation.

- thermalDissipationEff()
  corresponds to the energy lost due to effective viscous efffects.
  Everything that is lost from momentum. Thus essentially assumes
  turbulent equilibrium, but is what STAR-CD and Fluent seem to be using.
  Thus even if it's wrong, provide it anyhow.

- minor consistency update in comments