Tag alias: hand_on_chest <-> hand_to_chest

Aliasing:
hand_on_chest -> hand_to_chest or
hand_to_chest -> hand_on_chest

Reason: They look visually identical.
We also have both *on and *to tags, but hand_to_chest sounds better IMO.

i admit i'm confused using them the first time. but i think the reason why they remain separate is the originator of the hand and to whose particular chest.

what appears to be identical, i guess, those need some cleaning.

Ah, nevermind. I'll try to clean some.