- Replace FoxitSans with LiberationSans: LiberationSans is already there (for XFA) and we can use it as a good replacement of FoxitSans. - For now we just try to substitue standard fonts, the strategy is the following: * we try to find a font locally from a hardcoded list; * if it fails then we use Liberation as fallback (only for Helvetica for the moment); * else we just fallback on the system serif/sansserif/monospace font.