TraceRay:
  rewrite TestConeHelper and TestTrajectoryConeHelper for #3399

  these now no longer use any bounding-radius approximations to
  figure out if an object will potentially be hit, but calculate
  the exact colvol surface distance taking spread into account

  added some visual debugging to show which objects are being
  considered in the quads along the ray by weapons that call
  these functions (mostly Cannons)