mode." Primary motivation for this is backward-compatibility with BSD
4.3 and cross-compatibility with other platforms, but it's also a
nice feature to have. Displays "[Press space to continue, 'q' to quit]"
at the normal more prompt, and display "[Press 'h' for instructions.]"
when the user gives an invalid command. Some academic environments like
to set the MORE environment variable to contain -d so that students have
an easier time using it, so it's helpful if we can support that option.
ghudson