Re: re-builder highlighting incorrect for more than 3 groupings

[martin rudalics]

> Wouldn't be easier just to define reb-match-[4-9]? Faces aren't
> exactly a scarce resource, and nine is the maximum re-builder is going
> to use anyway.

The maximum of nine expressions applies only in "sub-expression mode".
In "normal" mode you would have to settle on an appropriate strategy
anyway when there are more than nine subexpressions.  On the other hand,
in sub-expression mode one face is all you need - you could use say

(face-name (format "reb-match-%d" (if subexp 1 i)))

in `reb-update-overlays'.