Storage of single values became less efficient starting with OSCAR 1.6

[fingolfin]

One of the thing that's great about this new site is that one can really "see" many examples for the format and look at them and ponder whether they are as they should be.

So e.g. one can notice by looking at it that in OSCAR 1.0-1.5, we have

{
  "_ns": {"Oscar": ["https://github.com/oscar-system/Oscar.jl", "1.5.1"]},
  "_type": "ZZRingElem",
  "data": "42"
}

while in OSCAR 1.6 and later this was deoptimized to

{
  "_ns": {"Oscar": ["https://github.com/oscar-system/Oscar.jl", "1.7.0"]},
  "_type": {"name": "ZZRingElem", "params": {"_type": "ZZRing"}},
  "data": "42"
}