Use `circled` instead of `circle`

[T0mstone]

Context

For circled symbols, we currently use the .circle modifier. This creates a name conflict in the case of U+2A22 ⨢ "Plus sign with small circle above" and U+2295 ⊕ "Circled plus", which both ought to be named plus.circle under this convention.

Proposal

Rename .circle modifiers that correspond to circled variants to .circled. Similarly, rename .triangle and .square to .triangled and .squared for consistency.

Breaking changes

Many variants would become invalid. The exact list of such variants would be determined when implementing the proposal.

[Enivex]

Wouldn't it be better to rename the super obscure symbol rather than making every other name longer?

[MDLC01]

I think adding a single letter is fine given this allows for consistency, and thus greater predictability of symbol names.

Also, note that other existing modifiers tend to use similar grammar, such as .filled, .stroked, or .struck.

A possible alternative is to keep the current names, and when there is an ambiguity, such as with ⊕ and ⨢, chose one to be the "default", and use an appropriate modifier to select the other one. For example, ⊕ would be plus.circle, and ⨢ would be plus.circle.above. In this case, this only works because .above does not already mean something for plus.