The rule quotenotnested is only used by the RTF target.

But there's already the quotemaxdepth rule, which when set to 1, means no 
nesting in quotes.

Before removing quotenotnested, one must test if ti won't break the RTF target, 
since there's a difference in the acting of the two rules.

quotenotnested: at parsing, quotes are nested. When dumping the results, they 
are un-nested.

quotemaxdepth: at parsing, nested quotes are leveled up and joined with the 
mother quote. This is the desired behavior.