Add function USF_Damage.f90 [elmerice/UserFunctions] and Damage test-case

git-svn-id: svn://svn.code.sf.net/p/elmerfem/code/trunk@7079 04224531-1f84-46d8-96ce-875b9e37dce3
small fix


git-svn-id: svn://svn.code.sf.net/p/elmerfem/code/trunk@7080 04224531-1f84-46d8-96ce-875b9e37dce3