Feat/marionGoodLuck

This merge request is the result of 5 shadow merge requests :

1. feat/token-selection --> Issue #2 (closed)
2. fix/cval-input-corpus --> Issue #6 (closed)
3. fix/token-selector-token2span --> Issue #2 (closed)
4. feat/sav-load-spacy-pipelines --> Issue #20 (closed)
5. feat/loading-corpus --> Issue #8 (closed)