feat: add blc params in exporter. fix bme.

- add ballance params section and successive switch in virtools file exporter to allow user manually cancel sector group ensurance which give user a way to export component, not the whole level.
- add mirror matrix detection in bme creation. a mirror matrix will reverse triangle indice order. we need reverse it again when facing mirror matrix. this resolves the issue when applying term 3.
- use mirror, not rotation to create straight floor in bme which give a better looks in game.

bbp_ng/raw_jsons/streets.json

@@ -47,7 +47,7 @@
                     "is_sink": "is_sink",
                     "is_ribbon": "False"
                 },
-                "transform": "move(length, 5, 0) @ rot(0, 0, 180)"
+                "transform": "move(0, 5, 0) @ scale(1, -1, 1)"
             }
         ]
     },