Add halibut package

packages/halibut.rb

+require 'package'
+
+class Halibut < Package
+  description 'Halibut is a documentation production system, with elements similar to TeX, debiandoc-sgml, TeXinfo, and others.'
+  homepage 'https://www.chiark.greenend.org.uk/~sgtatham/halibut/'
+  version '1.2'
+  source_url 'https://www.chiark.greenend.org.uk/~sgtatham/halibut/halibut-1.2/halibut-1.2.tar.gz'
+  source_sha256 '1aedfb6240f27190c36a390fcac9ce732edbdbaa31c85ee675b994e2b083163f'
+
+  def self.build
+    system 'make'
+    FileUtils.cd('doc') do
+      system 'make'
+    end
+  end
+
+  def self.install
+    system "mkdir -p #{CREW_DEST_PREFIX}/bin"
+    system "mkdir -p #{CREW_DEST_PREFIX}/man/man1"
+    system "cp build/halibut #{CREW_DEST_PREFIX}/bin"
+    system "cp doc/halibut.1 #{CREW_DEST_PREFIX}/man/man1"
+  end
+end