PR: https://forum.opnsense.org/index.php?topic=2273.0

Not explained why added in 2012 and never touched since.  Also only
works on one device.

(network insight) work in progress, when local netflow collection is enabled it should be easy to test the progress so far by going to https://<address>/ui/diagnostics/networkinsight/

Brings it a littler close to how "services" category works now.

1,2,3, this is a test...

o polling is going away
o idiomaitic way to enable/disable arp handling
o where does ip version prefer really fit in?
o unhide checkbox captions, as redundant as they may seem

(legacy) cleanup and validate url alias download, closes https://github.com/opnsense/core/issues/877

Simple names to complete drop-down