rename cvmix_message to cvmix_log

Rename the module, also changed cvmix_message_init -> cvmix_log_init and
cvmix_erase_log -> cvmix_log_erase. Next up, moving some of the private
routines I started putting in driver modules into cvmix_io.
Move routine to write diagnostic log to cvmix_io

Moved the private routine cvmix_log_diag from cvmix_kpp_drv to the public
routine cvmix_log_write in cvmix_io. Also renamed ModuleName to ModName in
cvmix_kpp_drv to shorten some lines... need to propogate that through other
files as well.
ModuleName -> ModName, SubroutineName -> SubName
More changes to variable names to reduce line length (without loss of info)
Rename EchoNamelist -> EchoParams

Also renamed cvmix_log_namelist -> cvmix_log_params