Tidy up popup layouts

- Settings: labels in one column and switches and number buttons lined
  up in another, with margins inside the panel
- Log: title and margins; text no longer touches the panel edge
- Sync result: error list centred under its header, which now reads
  Errors instead of CatchedErrors
- About: text wraps inside the panel instead of running under the
  scrollbar
- Character select: wider panel, so the right column of characters is
  no longer right next to the scrollbar

new_character_select.tscn

@@ -16,12 +16,12 @@ panel = NodePath("CharacterPanel")
 [node name="CharacterPanel" type="Panel" parent="."]
 unique_name_in_owner = true
 layout_mode = 0
-offset_right = 1260.0
+offset_right = 1290.0
 offset_bottom = 665.0
 
 [node name="VBoxContainer" type="VBoxContainer" parent="CharacterPanel"]
 layout_mode = 0
-offset_right = 1263.0
+offset_right = 1290.0
 offset_bottom = 659.0
 size_flags_horizontal = 3