xattr: new tests dedicated to xattr. Currently test21f,test21d,test22f,test22d
xattr: adding test21s and test22s
core: MODULES management moved to run_test.sh
core: badly located test_finalize
allfs/xattr: prettier display
xattr: new test23[f,d,s]
core: better TEST_USER management
core: fixing bug in run_test.sh/core_test.sh logic
core: MODULES supports comma separated lists