Allow the user to add files

[GaetanRdn]

Like in Stackblitz, the possibility to add file from the file tree could be a great feature.

We could create bigger exercices, more difficult.

In my case, I am preparing a tutorial for Angular. And with it, we quickly need to create new files.

[tadjik1]

Same here, my course is about node.js, and creating and manipulating files is a must-have feature. Maybe I can contribute somehow and help with the implementation?

[AriPerkkio]

Created an issue for this: #263

[isaacplmann]

I would like the same feature.

I think the most straightforward way to implement this would be to have the FileTree component show the current file system instead of the predefined contents in the _files folder. When that mode is enabled, the file syncing can be turned off.

The terminal does allow you to create and modify files - they just don't show up in the FileTree. npm add cowsay && cat package.json will show the changes.