Hmm... you have a very interesting engine there. In fact, it's exactly the engine I use, but coded in a different way... DC Mail me with your email address and I'll send you a little tutorial with double-jumping in it. The way I code my engines allows it easily.
won't you look up at the skyline
at the mortar, block, and glass
and check out the reflections in my eyes?
you see they always used to be there
even when this all was grass
and I sang and danced about a high-rise