cmAlgorithms: Add some convenient typedefs.

Source/cmAlgorithms.h

@@ -178,6 +178,12 @@ private:
   const_iterator End;
 };
 
+typedef cmRange<std::vector<std::string>::const_iterator> cmStringRange;
+
+class cmListFileBacktrace;
+typedef
+cmRange<std::vector<cmListFileBacktrace>::const_iterator> cmBacktraceRange;
+
 template<typename Iter1, typename Iter2>
 cmRange<Iter1> cmMakeRange(Iter1 begin, Iter2 end)
 {