Support for <(sub|sup)> (Was: [this] as a synonym for [this][])

[Jelks Cabaniss]

David P Henderson wrote:
> 	Ba^2+^ + OH^-^
> ... 
>
> I realize that the first form is used for emphasis, but the second
> form for <sup> would work and is fairly clear in its meaning.

... and is very Markdown-like.  I like it.  

(And if you had two `^` characters in the same block that you wanted
literally, you could backslash escape them...)

Though where does that leave `<sub>`, not to mention a possible sharing of a
common syntax form between other common inlines -- *if* that's implemented?


OTOH, it could be a synonym/alias/alternate the same way we now have two
ways of expressing implicit links:

	Ba^2+^ + OH^-^

would be equivalent to

	Ba[^2+^] + OH[^-^]

(though your shorthand for subscripts wouldn't be possible because, as you
pointed out, the underscore is already taken for emphasis.)


/Jelks