[ANN] ruby_parser 3.9.0 Released

ruby_parser version 3.9.0 has been released!

* home: <https://github.com/seattlerb/ruby_parser>
* bugs: <https://github.com/seattlerb/ruby_parser/issues>
* rdoc: <http://docs.seattlerb.org/ruby_parser>

ruby_parser (RP) is a ruby parser written in pure ruby (utilizing
racc--which does by default use a C extension). RP's output is
the same as ParseTree's output: s-expressions using ruby's arrays and
base types.

As an example:

    def conditional1 arg1
      return 1 if arg1 == 0
      return 0
    end

becomes:

    s(:defn, :conditional1, s(:args, :arg1),
      s(:if,
        s(:call, s(:lvar, :arg1), :==, s(:lit, 0)),
        s(:return, s(:lit, 1)),
        nil),
      s(:return, s(:lit, 0)))

Tested against 801,039 files from the latest of all rubygems (as of 2013-05):

* 1.8 parser is at 99.9739% accuracy, 3.651 sigma
* 1.9 parser is at 99.9940% accuracy, 4.013 sigma
* 2.0 parser is at 99.9939% accuracy, 4.008 sigma

Changes:

### 3.9.0 / 2017-04-13

* 1 major enhancement:

  * Added tentative ruby 2.4 support. Probably missing things.

* 13 minor enhancements:

  * Added RubyParser.latest.
  * Added RubyParser::Parser.version to make version range comparisons easier
  * Changed superclasses of all parsers to RubyParser::Parser
  * Cleaned up a lot of the version specific code to be more generic/flexible.
  * Documented how to add new versions in README.
  * Moved RubyParser from ruby_parser_extras.rb into ruby_parser.rb to fix bootstrap issues.
  * Renamed RubyParserStuff#get_match_node to new_match. Aliased and deprecated.
  * Renamed RubyParserStuff#logop to logical_op. Aliased and deprecated.
  * Renamed RubyParserStuff#node_assign to new_assign. Aliased and deprecated.
  * Renamed all parsers to RubyParser::V##.
  * Revamped grammar preprocessing to make adding new versions easier.
  * RubyParser.for_current_ruby falls back to latest if current not available.
  * Subclasses of RubyParser::Parser register themselves into RubyParser::VERSIONS.

* 4 bug fixes:

  * Fixed `&.` after newline. (presidentbeef)
  * Fixed bug setting line number for hash literals to line of opening brace.
  * Fixed grammar preprocessing bug.
  * Properly handle kDO with no-parens stabby lambda. (presidentbeef)