Set offset and limit in parameter bag

* VuFindSearch/Backend/Solr/Backend.php (search): Set offset and limit
  in parameter bag.
* VuFindSearch/Backend/Solr/Connector.php (search): Change function signature,
  offset and limit contained in parameter bag.

module/VuFindSearch/src/VuFindSearch/Backend/Solr/Backend.php

@@ -169,8 +169,10 @@ class Backend implements BackendInterface, MoreLikeThis, RetrieveBatchInterface
             }
         }
 
+        $params->set('rows', $limit);
+        $params->set('start', $offset);
         $params->mergeWith($this->getQueryBuilder()->build($query));
-        $response   = $this->connector->search($params, $offset, $limit);
+        $response   = $this->connector->search($params);
         $collection = $this->createRecordCollection($response);
         $this->injectSourceIdentifier($collection);
 

module/VuFindSearch/src/VuFindSearch/Backend/Solr/Connector.php

@@ -208,15 +208,11 @@ class Connector
      * Execute a search.
      *
      * @param ParamBag $params Parameters
-     * @param integer  $offset Search offset
-     * @param integer  $limit  Search limit
      *
      * @return string
      */
-    public function search(ParamBag $params, $offset, $limit)
+    public function search(ParamBag $params)
     {
-        $params->set('start', $offset);
-        $params->set('rows', $limit);
         return $this->select($params);
     }