mpegts inputs: allow to disable init/idle scan per tuner/input, fixes #2475
mpegts network scan: remove debug printf(), add help for init+idle scan checkboxes
mpegts input: only cleanups for mi_output_lock
mpegts input: tiny optimization
mpegts input: add back last_mp, it should be safe

The PID subscriptions are protected using mi_output lock, so
the whole mpegts_input_process() subroutine should be safe
for the mp structure caching.
mpegts input: protect global variable mpegts_pid_skel using mutex

- the skel variable is shared in multiple thread
- also remove mpegts_pid_sub_skel, it's not used frequently
mpegts input: optimize the mpegts_mux_find_pid_() for last change
Fix double free of hdhomerun_debug_obj
Bug #2479
mpegts_mux_start: add flags to the trace log
mpegts input: another optimization for mpegts_mux_find_pid_()
mpegts_input_open_pid: fix the wrong variable assignment
mpegts scan: fix the wrong constant usage (idle scan)
Fix H264 packet merging, fixes #2480
WEBUI JS: Add start/stop times to epg dialog, more cosmetic changes for EPG/DVR dialogs
spawn: fix possible NULL dereferences
simplify file_readall()
spawn: do not use syslog calls in the child process

The syslog routines uses private mutex so it can cause
various crashes and other misbehaviour.

Use pipes to send messages from the child processes.
spawn: implement spawn_and_give_stdout()
IPTV: add pipe:// handler to read MPEG-TS stream from an external program
spawn: fix a compiler warning (unused-variable)