Added inferred types and missing length function.

test/inferred_types.ink

@@ -0,0 +1,17 @@
+bar :: () -> float {
+	return 5.0;
+}
+
+foo :: () -> float {
+	return bar();
+}
+
+vertex main :: (pos : float3 @position) -> float4 @position {
+	   f := 2.0;
+	   i := 10;
+	   f = foo();
+	   v2 := float2(2, 2);
+	   v3 := float3(2, 2, 3);
+	   v4 := float4(4, 5, 6, 7);
+	   return float4(1, 1, 1, 1);
+}