Craft property - engine cooldown, turns until mission abortion available

[Finnik723]

Add new RuleCraft property, loaded from YAML - engineCooldown: int, default 0 in constructor. If engineCooldown > 0, on calling BattlescapeState::btnAbortClick(Action *) check if SavedBattleGame *battleGame->getTurn() < engineCooldown, don't show AbortMissionState, instead display CustomBattleMessageState with BattleMessage:

title = "STR_ENGINE_COOLDOWN_TITLE"
content = "STR_ENGINE_COOLDOWN_CONTENT"
answer = "STR_OK"
background = "TAC00.SCR"