testing gravity in tests/bowling.lua, updated ag.setGravity() documentation

git-svn-id: svn://anubis/anaglym/trunk@201 99a6e188-d820-4881-8870-2d33a10e2619

tests/bowling.lua

@@ -53,6 +53,10 @@ function key_down_event(key)
     elseif (key == "c") then
         local c = ag.loadModel("crate")
         c:setPosition(-3, -3, 5)
+    elseif (key == "g") then
+        ag.setGravity(0, 0, 2)
+    elseif (key == "r") then
+        ag.setGravity(0, 0, -9.81)
     end
 end