Merge pull request #1523 from wrl/relative-gembox-nokeyword

Implement gembox-relative gemdir paths

tasks/mrbgem_spec.rake

@@ -297,6 +297,8 @@ module MRuby
 
   GemBox = Object.new
   class << GemBox
+    attr_accessor :path
+
     def new(&block); block.call(self); end
     def config=(obj); @config = obj; end
     def gem(gemdir, &block); @config.gem(gemdir, &block); end

tasks/mruby_build_gem.rake

@@ -3,17 +3,26 @@ module MRuby
     def gembox(gemboxfile)
       gembox = File.expand_path("#{gemboxfile}.gembox", "#{MRUBY_ROOT}/mrbgems")
       fail "Can't find gembox '#{gembox}'" unless File.exists?(gembox)
+
       GemBox.config = self
+      GemBox.path = gembox
+
       instance_eval File.read(gembox)
+
+      GemBox.path = nil
     end
 
     def gem(gemdir, &block)
       caller_dir = File.expand_path(File.dirname(/^(.*?):\d/.match(caller.first).to_a[1]))
+
       if gemdir.is_a?(Hash)
         gemdir = load_special_path_gem(gemdir)
+      elsif GemBox.path && gemdir.is_a?(String)
+        gemdir = File.expand_path(gemdir, File.dirname(GemBox.path))
       else
         gemdir = File.expand_path(gemdir, caller_dir)
       end
+
       gemrake = File.join(gemdir, "mrbgem.rake")
 
       fail "Can't find #{gemrake}" unless File.exists?(gemrake)