Write a function which finds all the anagrams in a vector of words. A word x is an anagram of word y if all the letters in x can be rearranged in a different order to form y. Your function should return a set of sets, where each sub-set is a group of words which are anagrams of each other. Each sub-set should have at least two words. Words without any anagrams should not be included in the result.
