Reverse dependencies for eigenclass

Latest version of the following gems require eigenclass

Gem	Version	Date	Downloads
arc-furnace +101 Thousand Downloads	`0.1.42` March 10, 2020	March 10, 2020	101 Thousand
spectator-attr_encrypted +33.5 Thousand Downloads	`1.1.3` February 23, 2011	February 23, 2011	33.5 Thousand
n8-attr_encrypted +11.4 Thousand Downloads	`1.1.3` September 20, 2010	September 20, 2010	11.4 Thousand