#1243 missing procs or wrong man

[harm olthof]

According to http://tcllib.sourceforge.net/doc/nmea.html there are two procs: ::nmea::close_port
and ::nmea::close_file, which don't seem to have been implemented.

There is a proc ::nmea::close, so either the documentation should be changed or the procs will have to be implemented.
I prefer the latter.