add CollisionVisualizer

dtool/Config.pp

@@ -349,6 +349,11 @@
 // possible.
 #defer DO_PSTATS $[or $[and $[HAVE_NET],$[< $[OPTIMIZE], 4]], $[DO_PSTATS]]
 
+// Do you want to build the debugging tools for recording and
+// visualizing intersection tests by the collision system?  Enabling
+// this increases runtime collision overhead just a tiny bit.
+#defer DO_COLLISION_RECORDING $[< $[OPTIMIZE], 4]
+
 // Do you want to include the "debug" and "spam" Notify messages?
 // Normally, these are stripped out when we build with OPTIMIZE = 4, but
 // sometimes it's useful to keep them around.  Redefine this in your

dtool/LocalSetup.pp

@@ -110,6 +110,10 @@ $[cdefine HAVE_BISON]
 /* Define if we want to use PStats.  */
 $[cdefine DO_PSTATS]
 
+/* Define if we want to provide collision system recording and
+   visualization tools. */
+$[cdefine DO_COLLISION_RECORDING]
+
 /* Define if we want to track callbacks from within the show code.  */
 $[cdefine TRACK_IN_INTERPRETER]