improve [un]marshalling of non-binder objects

this change introduces a new class LightFlattenable<> which is
a protocol to flatten simple objects that don't require
binders or file descriptors; the benefit of this protocol is that
it doesn't require the objects to have a virtual table and give us
a consitant way of doing this.

we also introduce an implementation of this protocol for
POD structures, LightFlattenablePod<>.

Parcel has been update to handle this protocol automatically.

Sensor, Rect, Point and Region now use this new protocol.

Change-Id: Icb3ce7fa1d785249eb666f39c2129f2fc143ea4a
diff --git a/include/ui/Point.h b/include/ui/Point.h
index 1653120..1d7f64d 100644
--- a/include/ui/Point.h
+++ b/include/ui/Point.h
@@ -17,11 +17,12 @@
 #ifndef ANDROID_UI_POINT
 #define ANDROID_UI_POINT
 
+#include <utils/Flattenable.h>
 #include <utils/TypeHelpers.h>
 
 namespace android {
 
-class Point
+class Point : public LightFlattenablePod<Point>
 {
 public:
     int x;