0.23.0

CHANGES:

• Drop Parser from the API (#263, @pitag-ha)

• Location: add set_filename and Error.get_location (#247, @pitag-ha)

• Drop dependency on OMP2 (#187, @pitag-ha)

• Make OMP1 a conflict (#255, @kit-ty-kate)

• Drop Syntaxerr from the public API. Doesn't affect any user in the
  ppx universe (#244, @pitag-ha)

• Add a lower-bound constraint for Sexplib0 (#240, @pitag-ha)

• Fix bug due to which unwanted public binaries got installed when installing
  ppxlib (#223, @pitag-ha)

• Add Keyword.is_keyword to check if a string is an OCaml keyword
  (#227, @pitag-ha)

• Remove Lexer.keyword_table: use Keyword.is_keyword instead
  (#227, @pitag-ha)

• Remove Lexer from the API: it was the same as the compiler-libs
  Lexer (#228, @pitag-ha)

• Remove the modules Ast_magic, Compiler_version, Js, Find_version,
  Convert, Extra_warnings, Location_error, Select_ast and
  Import_for_core from the API: they are meant for internal use and
  aren't used by any current downstream user in the
  ppx universe (#230, @pitag-ha)

• Remove compiler specific helper functions from Location. They aren't used
  by any current downstream user in the
  ppx universe (#238, @pitag-ha)

• Allow "%a" when using Location.Error.createf (#239, @mlasson)

• Fix in Location: make raise_errorf exception equivalent to exception
  Error (#242, @pitag-ha)

• Fix in Pprintast: correctly pretty print local type substitutions, e.g.
  type t := ... (#261, @matthewelse)

• Add Ast_pattern.esequence, for matching on any number of sequenced
  expressions e.g. do_a (); do_b (); .... (#264, @matthewelse)

• Expose a part of Ast_io in order to allow reading AST values from binary
  files (#270, @arozovyk)