Collaborative coding environment

Students should be able to work together on a group project, and see what each other is doing, edit simultaneously, etc.

It's an open question whether this should follow a source control model, or a Google Docs style collaborative editing. The latter would probably be better, given the ease of use and lower required complexity of projects, but it's also harder to build.

The issue names no files, tests, or entry points. First inspect the project architecture and compare a source-control model with Google Docs-style collaborative editing, then identify the components affected by simultaneous editing and activity visibility. Done should mean that students can work on the same group project together and see each other's changes.

Written by the indexing model from the issue text.