Default width of answer boxes in the plugin settings

[dbauer-ets]

Hello Philipp,

In connection with issue #126 , although not directly related to it, it would be convenient to be able to define default values for the answer boxes in the plugin settings. Here is what that might look like:

[PhilippImhof]

I think that is a good idea. It's rather easy to implement and does not add clutter to the edit form. I'll put that on the list of stuff to add.