Include more information in feedback messages

[Goodlyay]

In the case of commands that don't exist, it's very useful if the server echos back the actual word the user typed so that they can notice if they made a typo or not.
In the case of blocks it may not be very important, though it becomes more useful once the server supports custom blocks that any given client may not be able to see

[purifetchi]

Thanks for the report!

The chat command system is still a WIP, and what's now is kind of a placeholder for a proper system I wanted to develop. Expect changes there whenever I feel like coming back to this project.

As for the block destruction, that's actually a pretty good idea, thanks!