sinksmtp: shorten sinksmtp's software name

Including a version is both pointless (in the current form) since it's
made up and puts the greeting banner in the log over 80 characters, so
I just cut it out.
sinksmtp: add -pprof to enable net/http/pprof profile monitoring

We force fully detailed memory usage monitoring, which may be a mistake.
This entire feature is experimental.