osdn #43203: targeted to freeciv-3.1: Enable new combat_odds_scaled_veterancy in most of the supplied rulesets.
Proposed patch makes veterancy gaining odds to depend on how challenging the battle was on: civ2civ3 (default), multiplayer, sandbox, goldkeep/experimental, alien, webperimental, granularity.
This leaves civ1, civ2, classic, and stub without it.