Sigilante

- [x] add characteristic unique parsable aura format & parser - [x] improve pretty-printing

On characteristic aura syntax: The atom format has the leftmost byte containing the dimensionality (`1` for `@lv`, `2` for `@lm`), then for `@lm` the number of rows in the next...

Hmm. There isn't a canonical interpretation of `~`/0 in this scheme. Is that a problem? Should I shoehorn it in?

Well, my idea was to suffix the value with either `_` cab for vectors or `__` cabcab for matrices. NaNs are unified in the jets (like `@r`) so they should...

I added a special case for `~` as a `0x0`. `._` and `.__` are similar to tuple literal form, but don't actually collide. There are a lot of adjacent literal...

Current status: I have a pretty-printer which works. The current version distinguishes `hqds` types by the vector angle brackets. The atom literal parser is being cantankerous about fallthrough. Let's suppose...

Hmm, I wonder if I can trick it by `pfix dot sig` then `pose` `royl-rs` and `royl-rd`.

Trying to figure this out (the last comment didn't get anywhere useful): what makes `++pose` actually decide that a parsing attempt has failed?

```hoon |% ++ lago ~+ ;~ pfix dot ;~ pose :: (scan "..1_.2.3_" lago:tt) {1 3} syntax error > (scan "..~1_.~2.3_" lago:tt) [%lvd 0x140026666666666663ff0000000000000] the above with plug: > (scan...

Ah! But this seems to work: ```hoon |% ++ lago ~+ ;~ pfix dot ;~ pose (stag %lvs lago-lvs) (stag %lvd lago-lvd) == == :: ++ lago-lvd (cook lagd lago-base-d)...