[SL] 2.8.0 invoice.tex error depends on user settings

[Philippe J. <pj...@po...>]

since upgrade from 2.6 to 2.8 I get errors in invoice.tex printing due 
to underscore and % characters

When I use French-utf8 (or other except english) as preference user 
setting I get a wrong behaviour; with english setting I get the correct 
printing of the same invoice.tex

-- 
Salutations Philippe JAOUEN	 GnuPG Key ID: 0xD103AAA8
Ferme du Ponctey :               http://www.ponctey.fr
cidre fermier du Pays de La Risle, Pommeau de Normandie et Calvados AOC