Save historic->modern dictionary to file

The reversed dictionary is saved as a json object to file. The name of
the file is the second command line argument of the script.
Improve output printed by the annotation_statistics script

Added some formatting to the output of the annotation_statistics script.
Update generate_historic_liwc script

We found out that the INL lexicon service only returns spelling variants
when the input is in lower case. Some of the words in the original Dutch
LIWC dictionary are written with (a) capital(s). The script was updated
to lowercase the terms send to the INL lexicon service.
Add script to generate text file from the debates data (xml)

Upon request by Inger Leemans. Adjusted the debates2csv script to save
all text in the xml file(s) to txt file(s).
Update folia2dataset_emo_sentences script to use folia tokenization

The folia2dataset_emo_sentences script was updated to use the folia
tokenization and print all folia words with a space between them for
each sentence. This makes tokenization easier for scikit learn (just
split on whitespace) and it makes it easier to create a spelling
normalized version of the data.