Tag Panel: horizontal layout improvements to tag fields

I had "The week of the Tag Panel" :smiley: I've rewritten the Tag Panel layout (again) and added the following improvements with the current Development Build Mp3tag v2.88c:

  • Tag Panel fields now fill up the vertical space and flow horizontally. If you want to exceed the available vertical space, you need to manually add _SEPARATOR fields where column breaks are needed.
  • Added context menu to customize fields,
  • Added option to specify size when adding fields (normal, smaller, small, multiline),
  • Added option to enable/disable fields.
  • Changed all Tag Panel fields to be customizable (incl. default fields)

It's clear that this needs thorough testing and I'm looking forward to your feedback