Rename helper spec: singleton_class(arg) -> eigenclass(arg)
Rename helper spec: singleton_class(arg) -> eigenclass(arg)

It was causing the most ridiculous non-sensical test failures, possibly a bug in Ruby itself, but this patch fixes it

jasonm23/pry,gfvcastro/pry,85x14/pry,printercu/pry,ooohiroyukiooo/pry,icebreaker/pry,josue804/debunker,gfvcastro/pry,printercu/pry,shockone/pry,tdg5/pry,nju520/pry,jasonm23/pry,raeno/pry,geoffreylitt/pry,scalixte-mdsol/pry,ngpestelos/pry,geoffreylitt/pry,jasnow/pry,nju520/pry,bronzdoc/pry,caporta/pry,jasonm23/pry,nju520/pry,jasnow/pry,shockone/pry,shockone/pry,tdg5/pry,raeno/pry,ngpestelos/pry,josue804/debunker,pvdb/pry,raeno/pry,caporta/pry,tdg5/pry,caporta/pry,bronzdoc/pry,jasnow/pry,icebreaker/pry,scalixte-mdsol/pry,ooohiroyukiooo/pry,85x14/pry,scalixte-mdsol/pry,85x14/pry,pvdb/pry,ooohiroyukiooo/pry