wrote query to sum up the number of watchlist entries for an exercise id, then wrote the test and merged development into my branch

This is no longer an enum, so we cannot reliably
translate it.

This accepts data from the updated backend
(from the previous commit) but does not display
any of the new metadata yet.

This is not tested with search results, because I could
not obtain search results locally. Suggestions on the
home page work, but no results are shown in /search

refactored statistics so that they are loaded by the statistics service and then resolved the collections bug

progress bar dispalys numbers now, trophy beside progress bar to see what kind of challenge the user is doing, reordered tropies, added disclaimer if no trophy has been achieved or if all trophies have been achieved, improved sql query to get both results at once, improved layout