Notation consistency with PyCLES

[ilopezgp]

Concerning the turbulence kinetic energy output:
In PyCLES, both the tke with density and without are outputs and named tke_mean and tke_nd_mean, respectively. For scampy, only tke_mean is an output, but it is NOT multiplied by the density.

Concerning the TKE budget terms:
In PyCLES, the tke_prod_X terms are not multiplied by the density.
In SCAMPy, however, the production terms, named tke_buoy and so on, ARE multiplied by the density.

I suggest homogenizing the notation, as the current choice might be misleading.