Windows build environment:

- Added build script
- Added build-installer script
- Added pack script
- Added gitlog script
- Use shadow build

build_scripts/Windows/env/env-msys.bat

@@ -0,0 +1,16 @@
+:: Usage:
+:: call find-in-path.bat [reinstall|clean]
+
+:: Initialize environment
+call "%~dp0env.bat"
+if errorlevel 1 goto error_env
+
+set EnvMSYSPath=%EnvRootPath%\msys
+
+call "%~dp0tools\prepare-msys.bat" %1
+exit /B %ERRORLEVEL%
+
+:error_env
+echo Failed to initialize environment.
+endlocal
+exit /B 1