Feedback/suggestions

Hi,
I was just playing a bit and generally like it, but have some feedback/suggestions:

1. The "No socket provided" error solution suggestion:
```
node ~/.config/mpv/scripts/mpvremote/remoteServer.js
No socket provided
```

That's a bummer, but:
```
node ~/.config/mpv/scripts/mpvremote/remoteServer.js '/tmp/mpvsockets/tmp.
v2mvVAeZGm'
listening on 192.168.2.2:8000
OSD message: Remote access on: 192.168.2.2:8000
OSD message: Pause
OSD message: Volume: 74%
OSD message: Volume 74
OSD message: Playing: movie.mkv
```
Well, look at that - as simple as manually providing the socket when automation fails, so instead of the error msg just notify/let the user provide it.

Theres a nice project (https://github.com/purarue/mpv-sockets) which provides usefull mpv scripts:

- mpv-active-sockets
- mpv-pick
- mpv-seek
- mpv-communicate
- mpv-play-pause
- mpv-song-description
- mpv-currently-playing
- mpv-quit-latest
- mpv-song-description-py
- mpv-get-property
- mpv-quit-pick
- mpv-next-song

IE. you could just do:
`node ~/.config/mpv/scripts/mpvremote/remoteServer.js "$(mpv-currently-playing)"`
as a fallback when normal run/start fails and problem solved.

2. Ive noticed that increasing/decreasing volume on remote doesn't show user any info on the phone. The info is visible only in the server log. It would be better to show the new changed volume value.

3. It would be nice to be able to control brightness/contrast as not every user is using a tv...

Just some crazy ideas from the top of my head... Thanks a lot for your work.