Bug#783875: No multi-arch

[nodiscc]

Would it be acceptable to show a debconf dialog/warning to the user?
For example


```
playonlinux requires a 32-bit installation of wine

Please make sure multi-arch is enabled:
	dpkg --add-architecture i386 && apt update
And install the wine:i386 package:
	apt install wine:i386
```

I spent some time debugging this before finding the bug report.
To make matters worse the playonlinux message is very vague.
I think reminding users to manually install a dependency would help
many.

Thanks