Move Lua wrapper code for Variants out of the Variant class file.

src/common/Object.h

@@ -78,6 +78,20 @@ private:
 
 }; // Object
 
+/**
+ * Structure wrapping an object and its associated Type instance. This is used
+ * for storing everything necessary to identify an object's properties in
+ * environments where the Type is not easily obtained otherwise, for example in
+ * a Lua state.
+ **/
+struct Proxy
+{
+	// Holds type information (see types.h).
+	love::Type *type;
+
+	// Pointer to the actual object.
+	Object *object;
+};
 
 enum class Acquire
 {