Diff -> Message
@tigill Just a quick hacky update to make the telegram message look nicer for cases where grade entries are added, since BV1 grades might come tomorrow already.
I noticed that there is a lot of overengineering potential here :) Currently the message string is fully constructed in the checker. However, the string is also dependent on the used notificator. For example, formatting like bold face differs in telegram markdown and email html. Rendering tables might work differently, also attaching images. Even newlines might be different.