Standard file lifecycle. Probably export too?

Edited by @sehyod:
Here are the subtasks for this tickets:

• Add ability to save files #197
• Add ability to create a new file #209
• Add ability to delete files #212
• Add ability to rename a file #213
• Add ability to export a file #214

This brings up the question of how to integrate these actions into the UI.
New file, Save and Export can all be added to a File menu on the top
Delete and Rename are trickier: the two entry points I can see for them are:

selecting a file in the explorer and pressing a keyboard shortcut (respectively F2 and Cmd+Backspace)
implementing a context menu