message: add stack filter
  hoping this is enough to make it work
diff: @@ -347,6 +347,9 @@ function SearchFilterCtrl($scope, dimSettingsService, dimStoreService, D2StoresS
  } else if (term.startsWith('light:')) {
  filter = term.replace('light:', '');
  addPredicate("light", filter);
  + } else if (term.startsWith('stack:')) {
  + filter = term.replace('stack:', '');
  + addPredicate("stack", filter);
  } else if (term.startsWith('level:')) {
  filter = term.replace('level:', '');
  addPredicate("level", filter);
  @@ -624,6 +627,9 @@ function SearchFilterCtrl($scope, dimSettingsService, dimStoreService, D2StoresS
  stackable: function(predicate, item) {
  return item.maxStackSize > 1;
  },
  + stack: function (predicate, item) {
  + return compareByOperand(vm.item.amount, predicate);
  + },
  engram: function(predicate, item) {
  return item.isEngram();
  },
  