stream_dvb: Record PIDs with human-readable content, bump max demuxer count.

There is the STD which contains service-names
(ffmpeg can understand it),
and the EIT which contains the EPG
(ffmpeg does not parse it, but e.g. VLC does).

As we now have more PIDs in general, increase the maximum
number of demuxers we can open. ffmpeg has an internal
limit of 64 PIDs, we are still far from that.

stream/dvbin.h

@@ -55,7 +55,7 @@
 #define DVB_CHANNEL_HIGHER 1
 
 #ifndef DMX_FILTER_SIZE
-#define DMX_FILTER_SIZE 16
+#define DMX_FILTER_SIZE 32
 #endif
 
 typedef struct {