Merge pull request #508 from dcdillon/patch-1

Added const_iterator to VectorBase

Author: eddelbuettel

inst/include/Rcpp/vector/VectorBase.h

@@ -135,6 +135,8 @@ class VectorBase : public traits::expands_to_logical__impl<RTYPE> {
 		R_xlen_t index;
 	} ;
 
+        typedef iterator const_iterator;
+
 	inline iterator begin() const { return iterator(*this, 0) ; }
 	inline iterator end() const { return iterator(*this, size() ) ; }