[Improvement] - Add an option to save the configuration of expanded/collapsed stuff

[ySergi]

I mean what things did you leave open, in my case I usually only monitor CPU and GPU temperatures, I don't care about the rest. I would like that when I re-open the program, everything stays as it is:

Also, it would be nice to be able to collapse all CPU cores and leave only "CPU Package" visible, since on CPUs with many cores it ends up being very large.

[pgrawehr]

This was already implemented, but broken on master. Should work again with master.