Better ASDF3 support, remove ASDF2 compatibility
Better ASDF3 support, remove ASDF2 compatibility

Now that Quicklisp carries ASDF3, there's no point in supporting ASDF2
any more

dkochmanski/cffi,mcna/cffi,dkochmanski/cffi,stassats/cffi,cffi/cffi,dkochmanski/cffi,mcna/cffi,stassats/cffi,attila-lendvai/cffi,cffi/cffi,cffi/cffi,stassats/cffi,attila-lendvai/cffi,3b/cffi,3b/cffi,3b/cffi