Changeling/say code bugfixes

Changelings can use hivechat while muzzled.  Issue #752
Monkey-lings can use hivechat.  Issue #564
Lings can return to human form even if monkeyed through genetics.  Issue #1084
One-line fix for Destroying Angels (..() wasn't being called)  Issue #3908
Spelling correction in Destroying Angel description.  Issue #NANWTFBBQ
Mimes cannot create invisible walls unless their vow of silence is active.  Issue #NaNi