[0.17.8] Map zoom speed irregular

[huwp]

Zooming out the map with the '-' shortcut key *zooms* out way too fast to be useful.

Resetting the in-game zoom to 100% with the shortcut 'F9' is very slow and stutters.

[thedarkbunny]

Having the same issue with the zoom-out key as of 0.17.11. Did some checking, and found the following:

- Tapping the zoom-in key seems to produce the same change as moving the scroll wheel by one notch.
- Scroll wheel operates consistently, with zoom-in and zoom-out speeds being equivalent.
- Tapping the zoom-out key results in about 10x the expected change in zoom.

Haven't tried using F9 to reset zoom, so can't comment there.

[Klonan]

Should be fixed