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/resolve/Namespaces.jet

@@ -1,5 +1,5 @@
 // FILE: f.kt
-~a~package a
+package ~a~a
     import java.*
 
     ~a.a~val a : util.List<Int>? = null