order groups and buttons alphabetically if weights are undefined or two elements have the same weights
order groups and buttons alphabetically if weights are undefined or two elements have the same weights

datavisyn/tdp_core,Caleydo/ordino,datavisyn/tdp_core,Caleydo/ordino,Caleydo/ordino,datavisyn/tdp_core,Caleydo/ordino,datavisyn/tdp_core