Disallow the operator= for btAlignedObjectArray, together with some fixes in the code (to avoid accidental deep copy)

Enable #define BT_ALLOW_ARRAY_COPY_OPERATOR in Bullet/LinearMath/btAlignedObjectArray.h to re-enable it
Fixes Issue 564, thanks to Tissen Peter for the report/fix

Extras/ConvexDecomposition/ConvexBuilder.cpp

@@ -251,7 +251,7 @@ bool ConvexBuilder::combineHulls(void)
 	if ( combine )
 	{
 		mChulls.clear();
-		mChulls = output;
+		mChulls.copyFromArray(output);
 		output.clear();
 	}