.bat files: initialize git submodules if necessary

clean.bat

@@ -1,3 +1,6 @@
+@if not exist "AvalonEdit\ICSharpCode.AvalonEdit.sln" (
+	git submodule update --init || exit /b 1
+)
 %windir%\microsoft.net\framework\v4.0.30319\msbuild /m ILSpy.sln /t:clean "/p:Platform=Any CPU" /p:Configuration=Debug
 @IF %ERRORLEVEL% NEQ 0 PAUSE
 %windir%\microsoft.net\framework\v4.0.30319\msbuild /m ILSpy.sln /t:clean "/p:Platform=Any CPU" /p:Configuration=Release

debugbuild.bat

@@ -1,3 +1,6 @@
+@if not exist "AvalonEdit\ICSharpCode.AvalonEdit.sln" (
+	git submodule update --init || exit /b 1
+)
 %windir%\microsoft.net\framework\v4.0.30319\msbuild /m ILSpy.sln /p:Configuration=Debug "/p:Platform=Any CPU"
 @IF %ERRORLEVEL% NEQ 0 GOTO err
 @exit /B 0

releasebuild.bat

@@ -1,3 +1,6 @@
+@if not exist "AvalonEdit\ICSharpCode.AvalonEdit.sln" (
+	git submodule update --init || exit /b 1
+)
 %windir%\microsoft.net\framework\v4.0.30319\msbuild /m ILSpy.sln /p:Configuration=Release "/p:Platform=Any CPU"
 @IF %ERRORLEVEL% NEQ 0 GOTO err
 @exit /B 0