add more shortcuts for zooming in

[jwetzell]

As noted I still contend this is a bug with electron. I still haven't found a single app where pressingctrl plus the key that + is on does not zoom in.

Closes #1256

[cpvalente]

I think this is what we can do from our side

As long as we feel like zooming is important to our users, we just need to commit to patch this up.

Thank you for the investigation and the fix 👍