All users see chat messages of other users

> Please provide us with the following information:
> ---------------------------------------------------------------

The chat shows messages written by any user to all users.

### This issue is for a: (mark with an `x`)
```
- [x ] bug report -> please search issues before submitting
- [ ] feature request
- [ ] documentation issue or request
- [ ] regression (a behavior that used to work and stopped in a new release)
```

### Minimal steps to reproduce
>
2 person chatting same time

### Any log messages given by the failure
>

### Expected/desired behavior
>
chat messages are only shown to person that wrote them.

### OS and Version?
> Windows 7, 8 or 10. Linux (which distribution). macOS (Yosemite? El Capitan? Sierra?)

### Versions
>

### Mention any other details that might be useful

> ---------------------------------------------------------------
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