dict/mapping values: do a simple verification of the value's
STIX version, not just its type. Added a lot more unit tests to
test behavior on dicts. To make the implementation work, I had
to move the detect_spec_version() function out of the parsing
module and into utils. So that required small changes at all
its previous call sites.
level with STIX versions in the same format as is used everywhere
else in the API: "X.Y", as opposed to the "vXY" format used by
the version-specific python packages. This eliminates all of
the awkward conversion from public API format to "vXX" format.
Also a little bit of code rearranging in the registration module
to ensure that some STIX 2.1-specific checks are done whether
version 2.1 is given explicitly or is defaulted to.
In the same module I also added a missing import of
stix2.properties, since my IDE was claiming it could not find a
function from that module.