Suggestion: tweak Skill Total filter

[samszotkowski]

Currently, if every option in the Skill Total filter is unselected, all skill total worlds appear on the list. So having them all unselected has the same effect as having them all selected. I propose making it so that having them all unselected removes all skill total worlds from the list (and maybe having them all selected by default if you want to keep the plugin's default behavior the same). Alternatively, you could add a "None" option to keep it consistent with the region and world type filters.

My current workaround is very simple, just set the subscription filter to members' worlds only and set the skill total filter to 500 only (F2P only), effectively filtering out all skill total worlds, but the behavior is slightly unintuitive.