Version 2.3.1

• Add \Slim\Slim::_isset and \Slim\Slim::__unset methods
• Add CONTRIBUTING file
• Add \Slim\Helper\Set::protect method to store Closure values that should not be invoked
• Fix encrypted cookie expiration time during serialization into HTTP header
• Fix Last-Modified and Expires header date format
• Fix \Slim\View::setData so that it protects Closures used as template variables

Version 2.3.0

• Added route groups
• Added resource locator
• Added HTTP PATCH method support
• Added new \Slim\Helper\Set interface
• Fixed XSS exploit in \Slim\Slim::urlFor method
• Simplified default error handler \Slim\Slim::handleErrors
• Removed \Slim\Middleware\PrettyExceptions when not in debug mode
• Let HTTP headers retain HTTP_ prefix if present
• Added \Slim\Helper\Set interface to \Slim\Http\Headers and \Slim\Http\Cookies
• Updated \Slim\Slim so that environment, request, response, router, log, and view are public properties.
• Updated \Slim\Http\Request and \Slim\Http\Response so that headers and cookies are public properties that implement \Slim\Helper\Set.
• Added \Slim\Http\Response methods setStatus(), getStatus(), setBody(), getBody(), and getLength()
• Updated \Slim\Http\Response object so that its cookies and headers are not serialized and encrypted until the very end of the app lifecycle.
• Updated \Slim\Log with PSR-3 interface
• Deprecated \Slim\Log::warn(), replaced with \Slim\Log::warning()
• Deprecated \Slim\Log::fatal(), replaced with \Slim\Log::critical()
• Deprecated \Slim\Http\Request methods cookies() and headers()
• Deprecated \Slim\Http\Response methods headers(), header(), length(), body(), status()
• Deprecated \Slim\Http\Response interfaces ArrayAccess, Countable, and IteratorAggregate