remove obsoleted api.
prepare migration.
ready to design new fluent api for io composition.
add io interface.
	new file:   WinSir.Tools.Photos/DirectoryProxy.cs
	new file:   WinSir.Tools.Photos/FileProxy.cs
	modified:   WinSir.Tools.Photos/IBasicIO.cs
	modified:   WinSir.Tools.Photos/IDirectoryIO.cs
	modified:   WinSir.Tools.Photos/IFileIO.cs
	modified:   WinSir.Tools.Photos/IOHelper.cs
	modified:   WinSir.Tools.Photos/WinSir.Tools.Photos.csproj
first TDD test case.
go ahead.
add possible thrid-party library.
rename.
add missing package. introduce new api structure.
change test logic.
add xunit.net test framework runner.
remove .DS_Store file. prepare runTests bash script.
add xunit.net project file.
add test script for *nix and windows.
adjust api structure.
abstract path.
rename fie and directory proxy.
introduce OSEnvironment. Remove Fluent.IO library.
FluentIO api.