Cataclysm-dda: Headless zombies

[Marrim]

Is your feature request related to a problem? Please describe.
Some zombie types imply heavy damage to the body prior to reanimation; crawling zombies most notably. It has been said that beheading does not stop zombies from reanimating, and some survivors might falsely assume it does.

Describe the solution you'd like
Some zombies should spawn as headless, a new zombie type, which may optionally have a new evolution line (characterized by lack of vision and scent but ablility to "hear" through sensing ground vibrations).

Describe alternatives you've considered
Sufficiently damaged zombie corpses reanimating as a lesser version (decayed/crawling/headless).

Additional context
N/A

[I-am-Erk]

Seems like a fair addition, the JSON would be fairly easy too.

[mlangsdorf]

https://github.com/CleverRaven/Cataclysm-DDA/wiki/Guide-to-adding-new-content-to-CDDA-for-first-time-modders

[Ilysen]

I think this might require some code to execute properly, so that ranged weapons' Headshot mechanic wouldn't show up. It'd be a little silly to headshot something with no head.

[nexusmrsep]

I believe there is a flag for that, that can be set for such monster.