Implement "Safe Delete" refactoring for named functions

Conflicts:
	idea/src/org/jetbrains/jet/plugin/refactoring/safeDelete/KotlinSafeDeleteProcessor.java

idea/testData/safeDelete/deleteFunction/implement2.kt

@@ -0,0 +1,13 @@
+trait A {
+    fun foo()
+}
+
+trait Z {
+    fun foo()
+}
+
+class B: A, Z {
+    override fun <caret>foo() {
+
+    }
+}