Fix: Prevent adding empty playlist items.
Updated German translation.
Updated Simplified Chinese translation.
DVB Header information for video streams

Added header information from PMT tables for MPEG-2 and H.264 Streams. The switching channel approach had to be reviewed as well.
Minimized the number of windows size changes each time a channel is switched

Signed-off-by: xpc1000 <xavier_portell@hotmail.com>
DVB: Add "No subtitles" to the stream selection menu.
Subtitles are disabled by default now.
Graph builder: Make duplicated filter detection stricter.

This let us blacklist filters more easily.
Blacklist some filters that are known to be incompatible with DVB.

This includes the internal video decoder for now (refs #730).