0.13.0

Breaking

• [AbstractTarget] The #sdk method now raises if the value is not the same
  across all the build configurations. This has been done to prevent clients
  from accidentally using arbitrary values.
  Fabio Pelosin

Enhancements

• [AbstractTarget] Added #resolved_build_setting and
  #common_resolved_build_setting.
  Fabio Pelosin
• [XCConfigurationList] Added #get_setting and #set_setting.
  Fabio Pelosin
• [Project] Added #build_configuration_list.
  Fabio Pelosin