Efl interface part: First draft.

This interface will be used for fetching parts from objects.
The parts can either be real objects or more likely mock objects
that proxy into actual calls on the object.

src/lib/efl/interfaces/efl_interface_part.eo

@@ -0,0 +1,18 @@
+interface Efl_Interface_Part {
+   legacy_prefix: null;
+   eo_prefix: efl;
+   properties {
+      part {
+         set {
+         }
+         get {
+         }
+         keys {
+            const char *name; /*@ part name. */
+         }
+         values {
+            Eo *pobj; /*@ the object that populates the part. */
+         }
+      }
+   }
+}