Move GUI sprites to the sprites/ folder

This is where vanilla will read the sprites from in future versions, so
means we have a consistent layout between versions.

Also move the turtle "selected slot" texture to a sprite sheet. It would
be good to do more of these in the future (e.g. printer progress, maybe
bits of printouts).

Sorry to resource pack artists for causing trouble again.

projects/common/src/client/java/dan200/computercraft/client/gui/GuiSprites.java

@@ -32,10 +32,13 @@ public final class GuiSprites extends TextureAtlasHolder {
     public static final ComputerTextures COMPUTER_COMMAND = computer("command", false, true);
     public static final ComputerTextures COMPUTER_COLOUR = computer("colour", true, false);
 
+    public static final ResourceLocation TURTLE_NORMAL_SELECTED_SLOT = new ResourceLocation(ComputerCraftAPI.MOD_ID, "gui/sprites/turtle_normal_selected_slot");
+    public static final ResourceLocation TURTLE_ADVANCED_SELECTED_SLOT = new ResourceLocation(ComputerCraftAPI.MOD_ID, "gui/sprites/turtle_advanced_selected_slot");
+
     private static ButtonTextures button(String name) {
         return new ButtonTextures(
-            new ResourceLocation(ComputerCraftAPI.MOD_ID, "gui/buttons/" + name),
-            new ResourceLocation(ComputerCraftAPI.MOD_ID, "gui/buttons/" + name + "_hover")
+            new ResourceLocation(ComputerCraftAPI.MOD_ID, "gui/sprites/buttons/" + name),
+            new ResourceLocation(ComputerCraftAPI.MOD_ID, "gui/sprites/buttons/" + name + "_hover")
         );
     }
 

projects/common/src/client/java/dan200/computercraft/client/gui/TurtleScreen.java

@@ -54,9 +54,9 @@ protected void renderBg(GuiGraphics graphics, float partialTicks, int mouseX, in
         if (slot >= 0) {
             var slotX = slot % 4;
             var slotY = slot / 4;
-            graphics.blit(texture,
-                leftPos + TURTLE_START_X - 2 + slotX * 18, topPos + PLAYER_START_Y - 2 + slotY * 18, 0,
-                0, 217, 24, 24, FULL_TEX_SIZE, FULL_TEX_SIZE
+            graphics.blit(
+                leftPos + TURTLE_START_X - 2 + slotX * 18, topPos + PLAYER_START_Y - 2 + slotY * 18, 0, 22, 22,
+                GuiSprites.get(advanced ? GuiSprites.TURTLE_ADVANCED_SELECTED_SLOT : GuiSprites.TURTLE_NORMAL_SELECTED_SLOT)
             );
         }
 

projects/common/src/datagen/java/dan200/computercraft/data/DataProviders.java

@@ -57,6 +57,7 @@ public static void add(GeneratorSink generator) {
                 LecternPrintoutModel.TEXTURE
             )));
             out.accept(GuiSprites.SPRITE_SHEET, makeSprites(
+                Stream.of(GuiSprites.TURTLE_NORMAL_SELECTED_SLOT, GuiSprites.TURTLE_ADVANCED_SELECTED_SLOT),
                 // Buttons
                 GuiSprites.TURNED_OFF.textures(),
                 GuiSprites.TURNED_ON.textures(),