Use more symbolic icons
Some icons in xfce4-panel preferences and dialogs were symbolic, some not (for examples, the Help button icon was not but the Close button icon was).
This switches nearly all of the rest of the icons to use symbolic icons. Also adds a little spacing between the icons and labels on some buttons.
One thing I could not figure out was where to change the right click menu icons (Properties, Move, Remove, Help, About, etc). I thought I'd changed it but it doesn't seem to change. Any direction on that would be appreciated.
Not sure if switching to more symbolic icons is even desired but was just did so out of curiousity and thought I'd submit it just in case it helps at all.
Edit, Glade 3.38 changed the two-worded properties from underscores to hyphens. That was an automatic change (changed last year it looks like). It makes the MR look bigger than it is. If that needs to be a separate MR I can do that.