schemas: Review all to ensure *schema* defines things as correctly as possible.

[Athanasius]

The general policy is that, as much as is feasible, a schema file alone should be enough to inform a Sender as to how to construct a compliant message.

outfitting/2, at least, has some shortcomings. It's explicit about excluding some things, but doesn't actually stop int_planetapproachsuite from being Relayed.

So, review all the schemas, tightening things up as per existing documentation.

In terms of branch/PR this should be done with a PR per schema. There's bound to be some changes that will need very careful consideration versus current Sender behaviour (especially taking into account where both CAPI and Journal data sources can be used). We don't want to hold up good changes because we're still hashing out the details of more troublesome ones.