Add namelist logging to cvmix_kpp_init

cvmix_kpp_init now requires an input of type(cvmix_message_type); as it sets
parameters in cvmix_kpp_params, it adds to the log (with status level
"EchoNamelist").

Doing this required a couple of additional auxiliary routines in cvmix_kpp (to
get non-real values out of the params_type) and cvmix_messages (to write
logical variables to the log).

I also swapped the "EchoNamelist" and "Diagnostic" status levels... so
selecting "EchoNamelist" will also include Diagnostics but "Diagnostics" will
not include the Namelist output (rather than vice-versa).