Replaced curved hill edge with a straight ramp to improve model placement.

Added Steam Vents at the far edges of the trenchline to fill in some dead space.

Updated to remove some exploitable terrain effects, and hopefully improve the map for combat forces.
1. The two central craters were removed - the stacked penalties from the Difficult Ground made it almost impossible for combat armies to cross the field.
2. The tall ruins were dropped down 1 floor - it was found that Deep Strikers could appear at the top of these structures even while enemies were at ground level, becoming entirely unchargeable while doing so.

Replaced the trees in the Forest terrain, which were not loading for all players.