Towards RegTAP 1.2

[Markus Demleitner]

Dear Registry,

Now that VODataService 1.2 is REC, we ought to reflect the cool new
stuff from there in RegTAP.

I've now prepared three github PRs that go some way there:
https://github.com/msdemlei/RegTAP/pulls.  I'd be grateful if you
could take a look and perhaps add an approving review.

Note that just because we merge a PR doesn't mean it'll be in REC --
for instance, I'm not convinced myself that in particular stc_spatial
(that *probably* presumes MOCs in the database, though perhaps it
could be implemented on top of some other representation) should be
part of the regular data model.

So, I'd say the question to answer when looking at the PRs is: Is
this material that should make it into the WD we'll discuss later?

Thanks,

           Markus