block spawning on ice slopes

So, was trying to allow spawning on level surfaces of ice but not girders, but seems to be failing. We'll call this WIP

Add checkins so that spawning on top of things is possible too

trying to eliminate that annoying impact sound for gears that are well under the water and not even exiting it. sheepluva might want to look this over since this is modifying his code and should perhaps be part of the addSplashForGear checks, but hadn't had much luck getting him to examine it past year or so

don't spawn things on ice. it's too unpredictable what'll happen to them

while we're tweaking this phrase, "with" feels awkward