Improve swid_measurement endpoint

[dbrgn]

Do a single query on the tags initially and read from the cached result afterwards.

See https://github.com/tnc-ba/strongTNC/commit/81fbe293d51f0dbe57c9da3946c4b5a206efbaee#commitcomment-6448018

[dbrgn]

Based on #250, so ignore the first commit.

This optimization reduces query time from ~1.5s to ~1s (with the debug server) for a big list of example tags I tried.

Please review, @d22.

[dbrgn]

@d22 fixed the settings issue & rebased!

[d22]

Good to merge!