Allow spectie's concordancer to accept an optional apertium mode and directory (implement via argparse). When it has these, it should run the corpus through that apertium mode and search against the resulting tags and lemmas as well as the surface forms. E.g., the form алдым might have the analysis via an apertium mode of ^алдым/алд<n><px1sg><nom>/ал<v><tv><ifi><p1><sg>, so a search for "px1sg" should bring up this word.