Add method Client::first

Author: danmichaelo

README.md

@@ -60,7 +60,14 @@ $client = new SruClient($url, array(
 ));
 ```
 
-To iterate over all the results from a `searchRetrieve` query, use the [Records](//scriptotek.github.io/php-sru-client/api_docs/Scriptotek/Sru/Records.html) class returned from `Client::records()`. The first argument is
+To get the first record matching a query:
+```php
+$client->first('bs.isbn="0415919118"');
+```
+The result is a [Record](//scriptotek.github.io/php-sru-client/api_docs/Scriptotek/Sru/Record.html)
+object, or `null` if not found.
+
+To iterate over all the results from a `searchRetrieve` query, use the [Records](//scriptotek.github.io/php-sru-client/api_docs/Scriptotek/Sru/Records.html) object returned from `Client::records()`. The first argument is
 the CQL query, and the second optional argument is the number of records to fetch for each request (defaults to 10).
 
 ```php

src/Client.php

@@ -160,6 +160,20 @@ public function records($cql, $count = 10, $extraParams = array(), $httpClient =
         return new Records($cql, $this, $count, $extraParams, $httpClient);
     }
 
+    /**
+     * Perform a searchRetrieve request and return first record
+     *
+     * @param string $cql
+     * @param array $extraParams Extra GET parameters
+     * @param mixed $httpClient A http client
+     * @return Record
+     */
+    public function first($cql, $extraParams = array(), $httpClient = null)
+    {
+        $recs = new Records($cql, $this, 1, $extraParams, $httpClient);
+        return $recs->numberOfRecords() ? $recs->current() : null;
+    }
+
     /**
      * Perform an explain request
      *