Ticket #2135: End button in MC viewer jumps too far
Previous solutions have broken one of the viewer features (http://www.midnight-commander.org/ticket/1778)
What suggest is fixing PgDn in a way, that it switches to one-line mode after EOF and add a check to ensure,
that at least one last line stays visible (4.7.1 behaviour of end/pgdn was irritating indeed).
With this patch, PageDown at the last page scrolls file line by line instead of entire page.
This is feature, not a bug. :)
Signed-off-by: Slava Zanko <slavazanko@gmail.com>