Refactored polling.

The original patch is polished and tweaked by Rolf Ahrenberg.
Implemented a preliminary state machine for tuner.
Tweaked error messages.
Fixed cSatipTuner::Connect().
Fixed cSatipTuner::Disconnect().
merge commit 'ede0294' into poller-stefan

reimported merge of rofafor
Conflicts:
	.gitignore
	Makefile
	poller.c
	pollerif.h
	rtcp.c
	rtcp.h
	rtp.c
	rtp.h
	tuner.c
	tuner.h
Merge remote-tracking branch 'upstream/poller' into poller-stefan