Msbuild: WriteLinesToFile should create the directory if it doesn't exist

[KirillOsenkov]

The WriteLinesToFile task doesn't create the directory for the file if it doesn't exist.

It should call Directory.CreateDirectory(Path.GetDirectoryName(File)) to help with the pit of success. Too much ceremony with requiring authors to create the directory themselves.

[CodeTherapist]

I would like to implement this.

[Therzok]

@CodeTherapist this should be a good start, and where the task lives: https://github.com/Microsoft/msbuild/blob/master/src/Tasks/FileIO/WriteLinesToFile.cs#L15

[rainersigwald]

All yours, @CodeTherapist. Let us know if you need any help.

[CodeTherapist]

@rainersigwald, @Therzok: Thank you for your helpfulnes :)