added additional metadata fields -> difficulty, education level, status, type, version, format, keywords, requirements

Merge remote-tracking branch 'origin/8-umsetzung-der-graphischen-oberflache-von-gernot' into 8-umsetzung-der-graphischen-oberflache-von-gernot

Create object for metadata search query.
This object is part of the SearchInputDTO object,
which gets parsed from the JSON file sent by the
front-end.

very inefficient :-) )

'origin/9-oauth2-authentisierung-auf-jwt-aufsetzen' into
8-umsetzung-der-graphischen-oberflache-von-gernot

layouting

Check optional metadata fields before
trying to display them.

Merge branch '8-umsetzung-der-graphischen-oberflache-von-gernot' of https://git.uibk.ac.at/csar9407/gitsearch.git into 8-umsetzung-der-graphischen-oberflache-von-gernot

When scrolling through the search results,
load new results when the bottom of the page
is near.

Merge branch '8-umsetzung-der-graphischen-oberflache-von-gernot' of https://git.uibk.ac.at/csar9407/gitsearch.git into 8-umsetzung-der-graphischen-oberflache-von-gernot