Stop only front wheels on pinch

TODO.txt

@@ -1,5 +1,7 @@
 =========== GENERAL ==============
 
+- improve the car unstucking? maybe we can just keep the position of the car
+  and ONE wheel (other joint positions can be computed)
 - some kind of special map block that would say where 3D triangles don't have
   to be drawn? could optimize rendering and map loading a lot
 - maps to make:
@@ -18,6 +20,7 @@
     - some speed map
     - some (at least partially) interior map
     - something with multiple finishes
+    - U-ramp to build speed and jump up to catch a CP
 - try to speed up the slow culling
 - make a small txt game menual
 - test: