1.647 Update - snowmobiles and more

Added snowmobile, industrial lights and new year gong.
Added new outputs to SAM site, same setup as the auto turret.
Fixed rockets not knocking out blocks in stability mode.
Sub can now be placed on the ground and building blocks.
Patched in after the last update:
Floors no longer block bunker roofs.
Fixed flat scene z-fighting with low foundations.
Changing selection tier in edit mode doesn't change current building tier.
Optimized Select Structure in edit mode.
Added RSS reader to add title/link for the latest update in main menu (mouse over Fortify).