Clean up the usage message, both in usage() and in the main program

Clean up the usage message, both in usage() and in the main program
comment, both stylistically (sort and combine options) and for
accuracy (following the manual page, make note of the -s and -S flags,
and use the term 'send' instead of 'say' to reduce confusion (SAY is
the name of a command for output to the user, not the connection.))