Store "minimize on join" for MUCs locally, as it is occasionally lost
I have a group chat configured with "minimize on join" and "join automatically". (If these terms are not exactly the English words shown in the GUI then this is because Gajim has selected German on my machine and I have not yet found a way to switch to English manually.) Anyway, what happens is that sometimes, when I start Gajim, it joins the group chat and the group chat window pops up on the screen. When I check, the setting to "minimize on join" has been disabled. I re-enabled it many times, but Gajim disabled it from time to time. This is with Gajim 1.1.0 on Windows 10, but I have seen the same problem also on Linux with older versions (pre 1.0).