+/*!
+ *\brief add contents of one vector to another vector uniquely.
+ *\param target Reference to the target vector.
+ *\param source Reference to the vector whose contents are to be added
+ * to target.
+ */
+template<typename T>
+void merge_vector_unique(vector<T> &target, const vector<T> & source){
+ for (unsigned int isource=0; isource<source.size();isource++){
+ bool already_present=false;
+ for (unsigned int itarget=0;itarget<target.size();itarget++)
+ if (target[itarget]==source[isource]){
+ already_present=true;
+ break;
+ }
+ if (!already_present) target.insert(target.begin(),source[isource]);
+ }
+}