iOS: Fix some memory leaks and remove unnecessary code. Like on Mac we need to release the item being packed in dw_box_pack_*(). However we don't need the retains or autoreleases since we use ARC on iOS. The UIWindow release is not necessary, garbage collection will remove it.

# Set these here to change the version for all platforms
DW_MAJOR_VERSION=3
DW_MINOR_VERSION=3