[Feature] Add length of source and target utterance

[fusaroli]

Specific case study: with parent-child interactions one might wonder whether there are different patterns when excluding shorter or longer utterances. Therefore it'd be useful to add columns with this information. This is probably overkill for most adult-adult conversations, tho'.

[nickduran]

To do so, add the following lines of code to the returnMultilevelAlignment function in "calculate_alignmnet"

utterance_length1 = {}
utterance_length2 = {}

 # add number of tokens in each utterance
utterance_length1['utterance_length1'] = len(tok1)
dictionaries_list.append(utterance_length1.copy())   

utterance_length2['utterance_length2'] = len(tok2)
dictionaries_list.append(utterance_length2.copy())