added ag::isKeyDown; Engine keeping track of which keys are currently pressed

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

tests/ballstairs.lua

@@ -2,6 +2,9 @@
 function update_event()
     ballx, bally, ballz = ball:getPosition()
     ag.setCamera(7, -6, 15, ballx, bally, ballz, 0, 0, 1)
+    if (ag.isKeyDown("m")) then
+        ball:setPosition(-7, 7.4, 12)
+    end
 end
 
 function key_pressed_event(key)