[0.12.19] inelegant message on double run

[navry]

When you run Factorio when another instance is already running, it shows an ugly message.

Not really a critical thing, might be done better (e.g. "Factorio is already running", or switch to the other window).
Also, probably not version specific.

[Kayanor]

For me it shows that:

[posila]

We don't forbid or prevent multiple instances of Factorio running on one computer, in fact we use it all the time. Problem is that the second instance of Factorio can't rotate factorio-current.log to factorio-previous.log as factorio-current is opened by the first instance.

It seams like navry's error message is localized and is cut off at the first non English character (I guess was supposed to say "Proces nemůže" ...)