Display text over borders like VSFilter.

If a style "A" is seen to contain a non-zero outline, add a generated style "A,0Outline" that is identical except for 0 outline width. For each dialogue that has style "A", add another identical one that has style "A,0Outline".

Some juggling with layers is required - if dialogue #10 got added to layer 2 but also has a 0Outline version, then the 0Outline version gets added to 2.5. All subsequent dialogues that would go to layer 2 go instead to (2 + Math.floor(2 + 1)) / 2 = 2.5. If one of these also has a 0Outline version, then this 0Outline version goes to layer (2.5 + Math.floor(2.5 + 1)) / 2 = 2.75 and so on.

{\rB} from a 0Outline dialogue gets redirected to the corresponding "B,0Outline" style.

This doesn't handle outlines generated dynamically using \bord, \xbord, ybord, but this is a stupid idea anyway so who cares?