Emote rework, invalid emotes are passed to ..(), slimes and cyborgs exem...

...pt

When an emote fails the switch check for a mob, it calls ..(act).
New files in mob/living and mob/living/carbon with associated procs that
handle these invalid emotes from higher emote calls.
If invalid on mob/living, mob/living will show the invalid emote dialog.
Slimes, Cyborgs, Larva, and MMIs do not call ..() on fail.

Example:
mob/living/carbon/human/emote("twitch")
    Not in switch(), so we call ..(act), which calls
mob/living/carbon/emote("twitch")
    Which is in this proc's switch(), so the effect is had.

Ex 2:
mob/living/carbon/human/emote("teleport")
    Does not exist here, ..(act)
mob/living/carbon/emote("teleport")
    Does not exist here, ..(act)
mob/living/emote("teleport")
    Does not exist here: Unusable emote 'teleport'. Say *help for a list.

Fixes #1221