SocketHandler: rename WritePMT to Write
Add support for OSCam network filtering

Filering of ECM/CAT/EMM packets is done localy (where the plugin/vdr)
is running. The filered data is sent back to OSCam via TCP network
socket. This way there is no need to have a real demux hardware where
OSCam is running, the dvbapi requests could be handled totally over
network.

minimal required OSCam version: r9580
Add OSCamHost and OSCamPort configuration options, update documentation.
Merge branch 'feature/netfilter'