Adding variables history

Added variables and tables history to schemas parsed from kwikly:

• Added a parsing_ressoures directory with two notebooks (one for parsing from kwikly, another to apply history changes to the schemas). Those are notebooks because we should only run them once, but it could be useful to have them if we would like to parse a more recent version of the kwikly.

• Update generation of tables for the dictionnary (adding two columns: 'creation' and 'suppression')

The schemas are upadated in two ways:

• For each field there are three new entries 'created':'2008', 'deleted':'2019', 'missings': '2010_2011_2012' where missings is for missing years of the variable
• For each table a new entry named history is added containing the same information as for variables (created, deleted, missings). Default values are fixed to '' (empty string) for deleted, created and missings but could be fixed to another value in the notebook add_variables_history_to_schemas.ipynb.