Subroutine to display online help information for GRAPHED.
The subroutine actually consists of a number of sub-modules, one for each of
the various commands used by GRAPHED, as well as a few for miscellaneous
information. It is internal to and called by the program GRAPHED.
call graphelpg (helpkey)
helpkey - GRAPHED command key for which help is desired, or an 'H' or '?'
to start at the top of the help information