add RGSS 3.0.1 etc classes equality comparison

RGSS 3.0.1 finally fixed #==, #===, #eql? for Color, Tone, and Rect.
Now instances of them can be compared to other kinds of objects.

binding-mri/etc-binding.cpp

@@ -22,6 +22,7 @@
 #include "etc.h"
 #include "binding-util.h"
 #include "serializable-binding.h"
+#include "sharedstate.h"
 
 DEF_TYPE(Color);
 DEF_TYPE(Tone);
@@ -68,6 +69,9 @@ ATTR_INT_RW(Rect, Height)
 		VALUE otherObj; \
 		Klass *other; \
 		rb_get_args(argc, argv, "o", &otherObj RB_ARG_END); \
+		if (rgssVer >= 3) \
+			if (!rb_typeddata_is_kind_of(otherObj, &Klass##Type)) \
+				return Qfalse; \
 		other = getPrivateDataCheck<Klass>(otherObj, Klass##Type); \
 		return rb_bool_new(*p == *other); \
 	}