Add /sit and /crawl Commands

[promsoyer]

I think the player experience would benefit from having commands like GSit.

[nelsongraca]

Considering we are getting cushions on 26.3 I'm not sure if it's worth the time. I am aware that for older versions can still be useful.

[scmcgowen]

/crawl would be mildly useful regardless of if cushions exist

[nelsongraca]

good point, I'll think over it when I can