Remove Sourcecast and Sourcereel

[martin-henz]

@sayomaki @boydanderson and I discussed and propose that we remove the features sourceCast and sourceReel from the frontend and the backend. This will allow us to focus the development effort more and reduce the complexity of the system.

[RichDom2185]

I discussed this with Prof @martin-henz earlier and we think there's still potential for these two features to be revived sometime in the future (perhaps by a CP3108 team). Plus, these two features are not blocking any of our planned changes/migrations at the moment, so there's no strong reason to necessitate their removal in the short-term future.

[martin-henz]

That's great. Let's keep them around and try to revive next year.