the receiver should be included in ancestors even when it's a singleton class
Merge branch 'master' of github.com:mruby/mruby
Merge branch 'master' of github.com:mruby/mruby
sort mrbgem's mrblib/*.rb files

 - https://github.com/mruby/mruby/commit/5de9a8cc50052db105ea8ba06d64b95cb1b57db1
Implement GemList which can identify GEM duplicates
Use advanced GemList as list for GEMs
Move GemList to MRuby::Gem::List. More logical location
Merge pull request #1232 from iij/pr-mrbgems-mrblib-sort

sort mrbgem's mrblib/*.rb files
Merge branch 'gem-duplication' of https://github.com/bovi/mruby into bovi-gem-duplication
avoid subclassing Array not to inherit too much methods
remove explicit check to honor duck typing
Merge branch 'master' of github.com:mruby/mruby
Merge branch 'bovi-gem-duplication'