This commit removed functions/events that have been deprecated in Bro
2.6. It also removes the detection code that checks if the old
communication framework is used (since all the functions that are
checked were removed).
Addresses parts of GH-243
* 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"
* origin/topic/vladg/dhcp_event_deprecation:
Add script to support the old DHCP events
Updated coverage tests and fixed incorrect DHCP:: scoping on some things
