C++: GCC prior to 4.7 does not support the override keyword. So if using earlier versions of GCC, just remove override. This allows compilation on ancient GCC and GCC based Xcode. Also remove virtual from the application, I don't think it is needed and old GCC pukes on it when it is there.

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