libav muxer: added WEBM support
descrambler: fix TSS_NO_ACCESS reset for buffered packets
remove pkt_merge_header()

- rename pkt_header to pkt_meta
- unify logic for the metadata processing
- add meta field to components to the htsp stream start message
htsp: log subsystem should be lowercase
transcoding: simplify streaming_start_t structure copy
WebTV: Implement basic touchscreen-compatible navigation controls, inc. paging and scrolling channel list
WebTV: Add Home/End, PgUp/PgDn, Left/Right plus overall code cosmetics
WebTV: Code cosmetics
WebTV: Code cosmetics
WebTV: Correct next/prev (esp. final page); add on-screen controls
WebTV: Remove unused parameters to navup/navdown
WebTV: Correct remote sort (defaultL: by channel number)