Release v0.20.0-RC2

Highlights:
Http4s 0.21.0-RC2 support
Ability to add tags to the entire swagger doc
Improvements to sealed traits support in swagger.

Details:

#377 Update http4s-blaze-server, http4s-dsl, ... to 0.21.0-RC2
#368 Update scala-collection-compat to 2.1.3
#361 Update swagger-core, swagger-models to 1.6.0

#352 Make it possible to add tag descriptions
#350 Add StringParser.map and StringParser.rmap
#357 Allow mixing case classes and case objects in selaed traits.
#359 Generate precise consumed media types
#358 Fix validation failures caused by Unit/Void/Nothing/Null

Thanks to @RafalSumislawski, @erdeszt

Release v0.20.0-M1

Update to 0.21.0-M5 of Http4s.
Added support for Scala 2.13.

Release v0.19.0

Release of 0.19.0:

Differences from last milestone:
Adds support for tagging routes.

Release v0.19.0-M8

Update to Http4s-0.20.0 Final
Refactor RhoDSL to allow custom responses for bad Query/Header parameters

Release v0.19.0-M7

Updates to http4s v0.20.0-RC1
Fixed Header Captures 'default' semantics #300
Fixed POST Route's to have easier query string parameters #301
Fixed Swagger output to maintain path order #299
Fixed Swagger output to mark non-option body parameters as required #295

Release v0.19.0-M6

Updates to http4s v0.20.0-M6
Fixes issue #216

Release v0.19.0-M5

Increment version