[godot] Improve Windows setup script.

spine-godot/setup.bat

@@ -1,7 +1,25 @@
-rmdir godot /s /q
-git clone --depth 1 https://github.com/godotengine/godot.git -b 3.4.4-stable
-xcopy /E /I .idea godot\.idea
-copy custom.py godot
-rmdir spine_godot\spine-cpp /s /q
-xcopy /E /I ..\spine-cpp\spine-cpp spine_godot\spine-cpp
-build.bat
+@echo off
+if [%1]==[] goto usage
+
+set branch=%1
+rmdir godot /s /q || goto error
+git clone --depth 1 https://github.com/godotengine/godot.git -b %branch%  || goto error
+xcopy /E /I .idea godot\.idea  || goto error
+copy custom.py godot  || goto error
+rmdir spine_godot\spine-cpp /s /q  || goto error
+xcopy /E /I ..\spine-cpp\spine-cpp spine_godot\spine-cpp  || goto error
+build.bat || goto error
+exit 0
+
+:usage
+@echo.
+@echo Usage^: setup.bat ^<godot_branch_or_tag^>
+@echo.    
+@echo e.g.:
+@echo        setup.bat 3.4.4-stable
+@echo        setup.bat master
+exit 1
+
+:error
+@echo Couldn^'t setup Godot
+exit 1