Added constructor to instantiate newDatetimeVector from VectorBase.

Author: dcdillon

inst/include/Rcpp/date_datetime/newDatetimeVector.h

@@ -28,10 +28,15 @@ namespace Rcpp {
 
     class newDatetimeVector : public NumericVector {
     public:
+        template <int RTYPE, bool NA, typename VEC>
+        newDatetimeVector( const VectorBase<RTYPE,NA,VEC>& other ) :
+            NumericVector(other) {}
+        
         newDatetimeVector(SEXP vec, const char* tz = "") :
             NumericVector(vec) {
             setClass(tz);
         }
+        
         newDatetimeVector(int n, const char* tz = "") :
             NumericVector(n) {
             setClass(tz);