Rename the existing fairland run to "plain".
New run "stunted" to cover larger minimal distances, islands
that can't fully grow, and islands that can't be placed.
New run "no-spike" to cover 0% spike.
New run "spike" to cover high spike percentage, mountains and -i.
Signed-off-by: Markus Armbruster <armbru@pond.sub.org>
