data: Parsing functions with ParseFunction for signature comparing

This change switches function and method parsing to use the structure ParseFunction, which holds all important values of
the function. This structure is then used also in call and usage parsing to allow distinction between signatures.

src/test/GraphTestSuite.h

@@ -397,6 +397,17 @@ public:
 		TS_ASSERT_EQUALS(c2, c3);
 	}
 
+	void test_graph_saves_nodes_as_undefined_function_when_using_signatures()
+	{
+		TestGraph graph;
+		Node* a1 = graph.createNodeHierarchyWithDistinctSignature("A", "A1");
+		Node* a2 = graph.createNodeHierarchyWithDistinctSignature("A", "A2");
+
+		TS_ASSERT_DIFFERS(a1, a2);
+		TS_ASSERT_EQUALS(a1->getType(), Node::NODE_UNDEFINED_FUNCTION);
+		TS_ASSERT_EQUALS(a2->getType(), Node::NODE_UNDEFINED_FUNCTION);
+	}
+
 	void test_graph_creates_multiple_nodes_as_undefined_nodes()
 	{
 		TestGraph graph;