Just's first parser performed both parsing, i.e the transformation of a
token stream according to the language grammar, and a number of consistency
checks and analysis passes.
This made parsing and analysis quite complex, so this diff introduces a
new, much cleaner `Parser`, and moves existing analysis into a dedicated
`Analyzer`.
Eventually, there will probably be a `crate` visibility specifier that
does the same thing as `pub(crate)`. This commit replaces `pub` with
`pub(crate)`, so when `crate` is available we can easily switch to it.
Just's dependency on brev was the cause of a
fairly deep branch of the transitive dependency
tree. To decrease build time and make the life of
packagers easier, this diff moves the functionality
that Just was using in Brev into Just itself, and
removes the dependency on Brev.
Fortunately, the only functionality that Just was
using was the output function and OutputError
enum, so this was easily done.
