Improve handling of superfluous hyphens when implicit bracketting

[dan2097]

e.g. 8-(3,5-Bis-trifluoromethyl-benzoyl)-3-furan-2-yl-methyl-1-o-tolyl-1,3,8-triaza-spiro[4.5]decane-2,4-dione should be treated as 8-(3,5-Bis-trifluoromethyl-benzoyl)-3-(furan-2-yl-methyl)-1-o-tolyl-1,3,8-triaza-spiro[4.5]decane-2,4-dione