remove stopwords from anytext filter

[pvgenuchten]

Overview

initial rough implementation to improve #879

q: seems only relevant to postgres, because fulltextsearch does not exist in plain sqlite.
q: it's probably better to retrieve stopwords from postgres, to prevent asynchronity, but also support stopwords for other languages ( i have not found how)

Related Issue / Discussion

#879

Additional Information

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[pvgenuchten]

problem seems caused by how full-text-search is implemented

where anytext_tsvector @@ to_tsquery('Aerial:*')
and anytext_tsvector @@ to_tsquery('of:*')

^^^ gives no results for titles like Photos of Aerial, below does give results:

where anytext_tsvector @@ to_tsquery('Aerial:* & of:*')