ScreenDrawing+Texture: Improve GUI sprite rendering

- Fix choppiness from using int coordinates
- UV order is normalised and flipping is explicitly not supported

src/main/java/io/github/cottonmc/cotton/gui/client/ScreenDrawing.java

@@ -132,8 +132,8 @@ public static void texturedRect(DrawContext context, int x, int y, int width, in
 					if (Float.isInfinite(fullWidth) || Float.isInfinite(fullHeight)) break outer;
 
 					// Calculate the offset left/top coordinates.
-					int xo = x - (int) (fullWidth * texture.u1());
-					int yo = y - (int) (fullHeight * texture.v1());
+					float xo = x - fullWidth * Math.min(texture.u1(), texture.u2());
+					float yo = y - fullHeight * Math.min(texture.v1(), texture.v2());
 
 					MatrixStack matrices = context.getMatrices();
 					matrices.push();

src/main/java/io/github/cottonmc/cotton/gui/widget/data/Texture.java

@@ -45,6 +45,8 @@
  * and they need to be drawn with specific {@code Texture}-accepting methods
  * or {@link net.minecraft.client.gui.DrawContext}.
  *
+ * <p>GUI sprite textures don't currently support flipping the texture by flipping UV coordinates.
+ *
  * @param image the image of this texture
  * @param type  the type of this texture
  * @param u1 the start U-coordinate, between 0 and 1