add dna_length function to Individual_7

src/libaevol/7/Individual_7.cpp

@@ -2132,4 +2132,12 @@ int32_t Individual_7::find_alignment(int32_t nb_tries,
   return cur_score;
 }
 
+int32_t Individual_7::dna_length(){
+  return annotated_chromosome_[A]->length()
+  #ifdef __EUKARYOTE
+  + annotated_chromosome_[B]->length()
+  #endif
+  ;
+}
+
 }

src/libaevol/7/Individual_7.h

@@ -149,6 +149,7 @@ class Individual_7 : public Observable {
   Chrsm parent2_gave_chrsm_;
   bool inverted_parents_;
 
+  int32_t dna_length();
 #ifdef PHENOTYPE_VECTOR
   double phenotype[PHENOTYPE_VECTOR_SIZE];
   double delta[PHENOTYPE_VECTOR_SIZE];