Zoom in with '=' in addition to '+', so holding shift isn't required

For some reason after the update to the zoom system was merged, I was able to _zoom out_ with the **minus key** but not _zoom in_ with the **plus key**. I decided to make the **equals key** _zoom in_ too so I could use that, and because it seems intuitive to press the key beside the **minus key** to perform the behaviour opposite to that of the **minus key**. After doing so however, I found both that the **minus key** and **equals key** zoomed out and in nicely, but that the **plus key** now worked as well (no idea why though).

In case the **plus key** works perfectly fine on your own configuration and you were curious, I'm using an up-to-date **Arch Linux** system with **jre8-openjdk**.

Cheers!