This commit includes the changes for the Godunov-like upwind scheme that
is used for the vertical discretization of turbulent advection terms in
rtp2, up2, vp2, thlp2, and rtpthlp equations (advance_xp2_xpyp_module.F90)
-- Change a logical namelist variable "l_godunov_upwind_xpyp_ta" to
turn off (.false., default) or turn on (.true.) the godunov upwind scheme
-- Changes in other codes are the adjustment of adding new namelist variables