VS Code Updates, master branch (2019.12.03.)

As discussed in https://gitlab.cern.ch/atlas-sit/CI/merge_requests/109, this MR adds CMakeLists.txt files to the "technical" subdirectories .vscode and .devcontainer. In order for this not to cause anything weird in the Athena project, I also told it to explicitly ignore those directories. (All other projects only include specific packages. The Athena project is the only one that generally includes everything, only excluding certain things.)

At the same time I was trying to make remote development using SSH connections a little easier. (https://code.visualstudio.com/docs/remote/ssh) Unfortunately I didn't really succeed at this. Unfortunately the sort of settings that are convenient for the users (as included in the settings.json file in this MR) can't be made on the "project level" apparently. They can only be made as global configuration options on the client machine.

Still, I thought it would be a good idea to add the recommended value of these settings to the repository, even if they aren't used. Just as a reference that we could point people at.

Finally (and this is not really a surprise), I am now able to develop athena code from Windows as well. 😉