[CODE] Import paths are now relative instead of absolute in parsing/

[ANOMALY] Fixed buggy behaviour of query type 'fields'

[CODE] Removed own API classes

ex: metadata.publication_date.year

- unwanted query keys lead to an error
- pagination is now available
- results can be sorted

- pagination support
- complex query support (9 operators, metadata & ngrams are fully queryable through joins)
- custom fields retrieval (TODO: aggregations)

[CODE] Added 'MatInit.py', so we have some starting data

[CODE] using SQLAlchemy for REST metadata retrieval
metadata retrieval is so much quicker now!

See: https://github.com/mathieurodic/aldjemy

Merge new feature

Fix

Last changes Alex

merge typo

Merge init

[BUGFIX] Europress Parser (adding language, get language from form, updating symlink towards treetagger.