Merge branch 'pb-hexanode' into development
unregister devicetree events on socket disconnect

otherwise we might leak memory, and we better not do that
add "forget device" button
set relay to "actor" instead of "sensor" in the registry
extend hexinfo json output to include information from the endpoint registry
Merge branch 'development' into pb-hexanode
periodically enumerate devices on the network
propagate all endpoint events to clients
add actors page to template
modularize endpoint visualizations

so far, only gauges are supported. coming up: buttons for boolean
actors!