[MSPAINT] Zoom out crashes

Hello,

I've discovered a bug in mspaint. Zooming out a picture with width/height equal or less to 7px will cause paint to divide by zero resulting in a crash of the application.

Build specifics are noted in the appcrash txt file attached to this report.

Version: 0.4.9-dev-686

Follow up to the merged fix;

Retest 955048e: Crashes less frequently. However, there's a bug with zooming in and out manually after changing the canvas size. I've created a scenario where base image is 1x1 and I resize it to 100x100. After some attempts of zooming out it switches back to 1x1 and attempts to divide by zero again. I'll provide the drwtsn report in a moment.