Zoom-IN to key KP_1, Zoom-OUT to key KP_3

[Bogdan107]

Is your feature request related to a problem? Please describe. No

Describe the solution you'd like I want this shortcuts to interactively zoom view:

• KP_1 - Zoom-IN
• KP_2 - Zoom-OUT

In my laptop:

• KP_1 - is key "1" on numeric block of keyboard, which has "1" and "INS" labels.
• KP_3 - is key "3" on numeric block of keyboard, which has "3" and "PG DN" labels.

# xev | grep keycode
keycode 87 (keysym 0xffb1, KP_1)
keycode 89 (keysym 0xffb3, KP_3)

Additional context Celestia not use shortcuts KP_1 and KP_3. So, KP_1 and KP_3 shortcuts are free to take new functions.