``NetControl::DROP`` had 3 conflicting definitions that could potentially
be used incorrectly without any warnings or type-checking errors.
Such enum redefinition conflicts are now caught and treated as errors,
so the ``NetControl::DROP`` enums had to be renamed:
* The use as enum of type ``Log::ID`` is renamed to ``NetControl::DROP_LOG``
* The use as enum of type ``NetControl::CatchReleaseInfo`` is renamed to
``NetControl::DROP_REQUESTED``
* The use as enum of type ``NetControl::RuleType`` is unchanged and still
named ``NetControl::DROP``
These are no longer loaded by default due to the performance impact they
cause simply by being loaded (they have event handlers for commonly
generated events) and they aren't generally useful enough to justify it.
* All "Broxygen" usages have been replaced in
code, documentation, filenames, etc.
* Sphinx roles/directives like ":bro:see" are now ":zeek:see"
* The "--broxygen" command-line option is now "--zeexygen"
