Add option to specify custom BPF filter

Can be useful in case of non standard network interfaces when like
tunnels or SPAN ports, when IP of interface does not match with IP of
packet.

Can be used to read traffic from multiple ports and interfaces at once
as well.

plugins.go

@@ -106,7 +106,7 @@ func InitPlugins() {
 	}
 
 	for _, options := range Settings.inputRAW {
-		registerPlugin(NewRAWInput, options, engine, Settings.inputRAWTrackResponse, Settings.inputRAWExpire, Settings.inputRAWRealIPHeader)
+		registerPlugin(NewRAWInput, options, engine, Settings.inputRAWTrackResponse, Settings.inputRAWExpire, Settings.inputRAWRealIPHeader, Settings.inputRAWBpfFilter)
 	}
 
 	for _, options := range Settings.inputTCP {