KT-1702 Renaming file causes "Operation not supported" and invalid imports

(Rename problem was caused because of invalid reference to file from package. Fix contains:
 - Change structure of references in package expression - last part is also a reference now
 - Resolve packages to expression but not to files)

  #KT-1702 fixed

compiler/testData/psi/SimpleModifiers.txt

@@ -8,7 +8,8 @@ JetFile: SimpleModifiers.jet
     REFERENCE_EXPRESSION
       PsiElement(IDENTIFIER)('bar')
     PsiElement(DOT)('.')
-    PsiElement(IDENTIFIER)('goo')
+    REFERENCE_EXPRESSION
+      PsiElement(IDENTIFIER)('goo')
   PsiWhiteSpace('\n\n')
   CLASS
     MODIFIER_LIST