Allow for external players command line parameters.

[ZaxonXP]

Is your feature request related to a problem? Please describe. Currently there is no way to do pause/play the stream from external command (see #82)

Describe the solution you'd like Allowing for external player command line configuration provide a way to control radioactive stream play/pause from external command (media buttons). In the configuration file there should be a section like player_cmd_parameters. For mpv I would use the following:

player_cmd_parameters=--input-ipc-server=/tmp/soc_mpv

Thís would allow controling mpv from external command like:

#!/bin/sh
# play
echo '{ "command": ["set", "pause", "no"] }' | socat - /tmp/soc_mpv

#!/bin/sh
# pause
echo '{ "command": ["set", "pause", "yes"] }' | socat - /tmp/soc_mpv