Validate user output

[wilzbach]

In the node world Nodeschool is pretty popular: http://nodeschool.io/#workshopper-list

You can see its online version here: http://generalhenry.com/

Their idea is pretty simple - download this guide and verification tool. Run it afterwards on your output to validate whether you did the right thing. Maybe the dlang-tour could do something similar to all those algorithm contest websites (e.g. hackerrank supports D) and check the user output.

[stonemaster]

Nice idea. There could be some sort of Exercise section which contains exercise for the readers.