MouseState equality operator bugfix.

Fixes a bug where the MouseState's equality operator does not check for XButton1 and XButton2.

Author: roys-coding

src/Input/MouseState.cs

@@ -144,7 +144,9 @@ ButtonState xButton2
 					left.LeftButton == right.LeftButton &&
 					left.MiddleButton == right.MiddleButton &&
 					left.RightButton == right.RightButton &&
-					left.ScrollWheelValue == right.ScrollWheelValue	);
+					left.ScrollWheelValue == right.ScrollWheelValue &&
+					left.XButton1 == right.XButton1 &&
+					left.XButton2 == right.XButton2 );
 		}
 
 		/// <summary>