Create: Coasters Simulated

-Track placement smoothing has new context based behaviors (perfect circles, 90 degree turns) -Rivets can no longer be placed on balloons -Fixed strange UI interaction when attempting to place a rivet inside a rivet -Better error messaging for cart linkage -Balloons now properly tether to the center of block models -Balloons can now be shift clicked with a wrench to be removed without popping other nearby balloons -Balloons can now be stacked to 64 instead of just 16