Zig 0.11 compatibility

The codebase has been ported to Zig 0.11
and the following bugs have been fixed:

* Missing bullet/crater holes on certain walls (from 2.4.6)
* Disruptive disappearance of decals
-----BEGIN PGP SIGNATURE-----

iHUEABYKAB0WIQSDiv4NVdwHTjYPlDqEtpzm8/a3ZwUCZOZeVwAKCRCEtpzm8/a3
Zw3dAP4m083Tgo2SG2QnlNmuJxXJ+tMC891/qrp5/gxNY+eR1wEApB2p59Zr02b0
gBL9t7rFLvZLrRCZDOuwHpW+4Y/I3ws=
=3CGx
-----END PGP SIGNATURE-----