The functions mapping elevation to resources are piecewise linear,
except for set_oil(), which randomly adds 1 to sea oil, and
set_gold(), which is isn't linear for mountains, but very close.
Drop the random oil bit, and replace the non-liner gold function by a
linear one. Both resources decrease at most by one point.
Signed-off-by: Markus Armbruster <armbru@pond.sub.org>
uid owner xloc yloc type effic mobil off tech opx opy mission radius fleet civil milit shell gun petrol iron dust bar food oil lcm hcm uw rad pstage ptime access name xbuilt ybuilt builder rflags rpath