My goal was to not break `no_std` support with them, so after some time
I've finally found `miette` and `thiserror` forks that seem to suppoert
`no_std`
- `Token`s are called `Selci` (selshi) now
- `Selci` do not own or statically refer to their data. Instead they
only contain some sort of span
- `Selci` are collected into `SelciTree` used to tranverse the AST
- All base `Selci`-related stuff (like their definitions, `SelciTree`
ddefinintion, convenience macro creation deifnition `SenciTree`
traversal, etc) are now to be separated into a dedicated crate
`kyomato-core`
- For more details on rework, see temporary item in `kyomato-core/lib.rs`
