new tilemap class

[Incubatio]

I made a new tilemap class, I invite you to take a look:
https://github.com/Incubatio/gamecs/blob/master/src/lib/tilemap.coffee

In addition to the old tilemap example I added another one :)
http://incubatio.github.com/gamecs/sc-examples.html#tilemap2

[oberhamsi]

looks good. i thought about dropping xml support because it doesn't work in IE but otoh i already have it :) i'll probably add json too.

the second example with collision is good. i was never sure whether to include collision logic because there's so many ways to do it.