Utils.hs: added a maybeHead (safe head) function to Utils.
Utils.hs: added a maybeHead (safe head) function to Utils.

darcs-hash:20071116012522-db1bb-62b4b38e766adc0479cc4b531714ba6e608a5207

cordawyn/rdf4h,LeifW/rdf4h,jutaro/rdf4h,ddssff/rdf4h