Make texts in the Dialogic translatable

[Tetragramat]

Is your feature request related to a problem? Please describe.
I have game that is not in English and I have to modify Dialogic to have for example history "joined", "left" and "Everyone left" translated.

Describe the solution you'd like
instead of using strings like character_name + " joined" use rather tr("{character} joined").format({"character": character_name}) so it can be translated.

Describe alternatives you've considered
I had to modify code of Dialogic.

Additional context
Dialogic 2 alpha 15. Haven't noticed any other texts other than "x joined", "x left" and "Everyone left". There is "History" button, but that should be translatable already.