0.7.12.57

0.7.12.57
	Add :force t to asdf-dependent contrib modules

	Change install.sh to rename old binary/core files instead of
	copying them - does not kill running SBCL programs in such a
	gruseome way

	Create $SBCL_HOME/site-systems in install.sh

	... OK, that's IT, I am DONE for 0.7.13