Add F2 screenshot functionality (#1262)

- Updated `EControllerActions` to include `MINECRAFT_ACTION_SCREENSHOT`.
- Added conditional compilation for `stb_image_write.h` in `Minecraft.cpp`.
- Modified `run_middle()` to handle screenshot key press.
- Updated `tick()` to capture and save screenshots as PNG files.
- Introduced `KEY_SCREENSHOT` in `KeyboardMouseInput.h` mapped to F2.
- Added `stb_image_write.h` for image writing capabilities.

Minecraft.Client/Minecraft.cpp

@@ -1553,6 +1553,9 @@ void Minecraft::run_middle()
 							localplayers[i]->ullButtonsPressed|=1LL<<MINECRAFT_ACTION_RENDER_DEBUG;
 						}
 
+						if(g_KBMInput.IsKeyPressed(KeyboardMouseInput::KEY_SCREENSHOT))
+							localplayers[i]->ullButtonsPressed|=1LL<<MINECRAFT_ACTION_SCREENSHOT;
+
 						// In flying mode, Shift held = sneak/descend
 						if(g_KBMInput.IsKBMActive() && g_KBMInput.IsKeyDown(KeyboardMouseInput::KEY_SNEAK))
 						{
@@ -3741,6 +3744,13 @@ void Minecraft::tick(bool bFirst, bool bUpdateTextures)
 			//options->thirdPersonView = !options->thirdPersonView;
 		}
 
+#ifdef _WINDOWS64
+		if(player->ullButtonsPressed&(1LL<<MINECRAFT_ACTION_SCREENSHOT))
+		{
+			RenderManager.DoScreenGrabOnNextPresent();
+		}
+#endif
+
 		if((player->ullButtonsPressed&(1LL<<MINECRAFT_ACTION_GAME_INFO)) && gameMode->isInputAllowed(MINECRAFT_ACTION_GAME_INFO))
 		{
 			ui.NavigateToScene(iPad,eUIScene_InGameInfoMenu);