[ANN] RDL 2.0.0 release - now with type checking!

I'm pleased to announce version 2.0.0 of RDL, a lightweight system for
adding types and contracts to Ruby. This major new release features
*type checking*, meaning RDL can "statically" check that a method body
matches its type, as a way of potentially detecting errors early in
development. For example:

  require 'rdl'

  type '(Fixnum) -> Fixnum', typecheck: :now
  def id(x)
$ ruby file.rb
.../lib/rdl/typecheck.rb:32:in `error':  (RDL::Typecheck::StaticTypeError)
.../file.rb:5:5: error: got type `String' where return type `Fixnum'
.../file.rb:5:     "forty-two"
.../file.rb:5:     ^~~~~~~~~~~

Notice type checking happens even without running the method. See the
README.md file for a much longer discussion.

This version of RDL also fixes a few bugs here and there with the
contract features of RDL (see list below.)

Comments, questions, suggestions, and complaints are all welcome!
Email me or post on the forum.


### Coordinates

* code/docs: https://github.com/plum-umd/rdl
* gem: https://rubygems.org/gems/rdl
* install: gem install rdl
* forum: https://groups.google.com/d/forum/rdl-users

### License

BSD 3-Clause

## [2.0.0] - 2016-08-24

### Added
- Static type checking!
- `wrap: false` optional argument to `type`, `pre`, and `post`
- Non-null type annotation (not checked)
- Default argument configuration for `type`, `pre`, and `post`
- `attr_*_type` methods
- Initial types for Rails

### Changed
- Modified `self` type to be any instance of the self's class
- Library types now use new aliases %integer and %numeric instead of the
Integer and Numeric classes
- Instead of requiring `rdl_types.rb`, require `types/core`

### Fixed
- Fix issue #14 - allow type/pre/post to coexist, improve docs on dependent
- Fix typos in README, pull req #13
- Fix bug where calling method overloaded sometimes with block and
sometimes without would always report type error