Tag alias: splash <-> splashing

splash <-> splashing
Reason: same thing.
Direction: Pretty sure we have a standard for this, but I can't remember it.

Usually to -ing.

Create alias: splash -> splashing

Edit: But then splashing implies a splasher, and "I see a splash in this image" seems more natural than "I see someone splashing in it".

I think it's fine to standardize on -ing even when the splasher isn't visible. Done.