Term Vector settings should be treated like flags without propergation

today if a specific feature is disabled for term vectors with something
like 'store_term_vector_positions = false' term vectors might be disabeled
alltogether even if 'store_term_vectors=true' in the mapping. This depends on the
order of the values in the mapping since the more specific one might override
the less specific on.

Closes #4582

src/main/java/org/elasticsearch/index/mapper/core/AbstractFieldMapper.java

@@ -117,24 +117,32 @@ public abstract class AbstractFieldMapper<T> implements FieldMapper<T> {
         }
 
         public T storeTermVectors(boolean termVectors) {
+            if (termVectors) {
                 this.fieldType.setStoreTermVectors(termVectors);
+            } // don't set it to false, it is default and might be flipped by a more specific option
             return builder;
         }
 
         public T storeTermVectorOffsets(boolean termVectorOffsets) {
+            if (termVectorOffsets) {
                 this.fieldType.setStoreTermVectors(termVectorOffsets);
+            }
             this.fieldType.setStoreTermVectorOffsets(termVectorOffsets);
             return builder;
         }
 
         public T storeTermVectorPositions(boolean termVectorPositions) {
+            if (termVectorPositions) {
                 this.fieldType.setStoreTermVectors(termVectorPositions);
+            }
             this.fieldType.setStoreTermVectorPositions(termVectorPositions);
             return builder;
         }
 
         public T storeTermVectorPayloads(boolean termVectorPayloads) {
+            if (termVectorPayloads) {
                 this.fieldType.setStoreTermVectors(termVectorPayloads);
+            }
             this.fieldType.setStoreTermVectorPayloads(termVectorPayloads);
             return builder;
         }