Remove packed attribute from Rect

Fixes #3785 -- the issue where the Travis build failed because of gcc's
-Werror=address-of-packed-member.

Adds an equality function to avoid relying on memcmp().

include/data.h

@@ -159,7 +159,7 @@ struct Rect {
     uint32_t y;
     uint32_t width;
     uint32_t height;
-} __attribute__((packed));
+};
 
 /**
  * Stores the reserved pixels on each screen edge read from a