Log Message:
graphics/rabbit: update to 2.2.1

pkgsrc change: add pkg_alternatives support.

== 2.2.1: 2017-09-15

For RubyKaigi 2017 speakers release.

=== Improvements

==== rabbit

  * Supported Rouge.

  * Suppressed warnings with Ruby 2.4.
    [GitHub#109][Patch by Nobuyoshi Nakada]

==== Theme

  * image-slide-number: Supported "extra slides".
    If you set "image-slide-number-last-slide" slide property to \ 
"true",
    image timer computes its position as the slide is the last slide.
    Image timer isn't moved for the following slides.

==== Document

  * Added a sample slide for RD style.
    [GitHub#105][Patch by Masayuki Morisaki]

  * Added a document how to prepare development environment.
    [GitHub#106][Patch by Masayuki Morisaki]

  * Removed license information for prototype.js that removed.
    [GitHub#107][Patch by Ryunosuke Sato]

=== Fixes

==== rabbit

  * Information windows: Fixed a source format detection failure.
    [GitHub#102][Patch by Akihisa Higuchi]

==== Document

  * Fixed style of sample page.
    [GitHub#103][Reported by takiy33]

=== Thanks

  * Akihisa Higuchi

  * takiy33

  * Masayuki Morisaki

  * Ryunosuke Sato

  * Nobuyoshi Nakada