Improvement: reset zoom with zero key about epr

[wustho]

Hey there Sandersantema, that's good feedback, thanks.

But I think it's better to wait dsanson from issue #5 for him to implement vim like prefix key, so when we press 6j we get cursor moved down six times. As for default text area width, I hope we can get it by prefixing 0 to =, furthermore we can get 120 columns text area width by simply 120= rather than holding =. Although we're probably not in hurry.

[wustho]

Hello there, looks like reset key is pretty useful, I just add it with 0 (zero) key in recent commit, sorry took a while