Remove tracklist and puid from our rewrites, update a few URLs which have changed
Remove huge commented out section
MBS-7470: Keep only the target's secondary types on RG merge

When merging release groups, all secondary types of all involved
release groups were combined; e.g., merging a "Live+Demo" RG into a
"Live+Soundtrack" RG resulted in "Live+Demo+Soundtrack". This was
perceived as unintuitive and usually undesirable, because often a
recently created duplicate RG with absurd types is merged into a
correct target. The behaviour is therefore changed to always discard
the other secondary types, only retaining those of the merge target.
Update tests for MBS-7470
MBS-6887: Model coordinates with required fields

Coordinates for places are stored in the database as a point data
type, which has always both latitude and longitude; only the point as
a whole can be NULL. Therefore, points should be modelled with
mandatory latitude and longitude fields in the server code, too,
instead of indicating the absence of coordinates by setting latitude
and longitude to undefined.

This also makes it more straightforward to test for coordinates being
present or not, avoiding problems like MBS-7450 (zero coordinates
interpreted as no coordinates).
Update place and coordinates tests for MBS-6887
Escape ampersand in OSM URLs
Add test for removing coordinates from a place
Make coordinate tests more sensitive for rounding issues
Merge remote-tracking branch 'nikki-bitbucket/rewrites' into beta

* nikki-bitbucket/rewrites:
  Remove huge commented out section
  Remove tracklist and puid from our rewrites, update a few URLs which have changed
Merge remote-tracking branch 'chirlu/mbs-6887' into beta

* chirlu/mbs-6887:
  Make coordinate tests more sensitive for rounding issues
  Add test for removing coordinates from a place
  Escape ampersand in OSM URLs
  Update place and coordinates tests for MBS-6887
  MBS-6887: Model coordinates with required fields
Merge remote-tracking branch 'chirlu/mbs-7470' into beta

* chirlu/mbs-7470:
  Update tests for MBS-7470
  MBS-7470: Keep only the target's secondary types on RG merge