* Reverted [pos.mli] to the previous signature, except [Pos.min]
that now takes a labelled parameter [file].
* Reverted [ParserAPI.ml] to the previous signature.
* Reexported [shor_error] in [ParserUnit].
* Changed the modules [LexToken] so that they export one function
to make attributes, the first, additional paramater being "[@"
or "[@@" (and invalid in PascaLIGO).
* Added support in all [ParserLog] for attributes (pretty-printings).
* Added AST nodes [Attr] and [AttrDecl] to PascaLIGO. The simplifier
takes care of hooking them with their respective declarations
or discarding them. (In the future, we should issue a warning for detached
attributes.)
* Duplicate variants in the same type declaration
* Duplicate parameter in the same function declaration
* Shadowing of predefined value in a declaration
I fixed the architecture for that support: ParserMain.ml is now where
those specific errors are handled, and they are produced by the
semantic actions of the parsers.
* I added CLI option "--mono" to select the monolithic API of Menhir.
* I added a field "win" to the state of the lexer (a two-token
window for error reporting).
* I escaped LIGO strings before making them OCaml strings (for
example for printing).
