Let Recorder remember its replayCharSequence, and ToeThread close it when uri

processing is finished.
* Recorder.java
    getReplayCharSequence() - remember ReplayCharSequence, obtain new one if
        none remembered or remembered has been closed
    endReplays() - close replayCharSequence
* ToeThread.java
    run() - call Recorder.endReplays() when finished with uri
* ReplayCharSequence.java
    isOpen() - return false if close() has been called
* GenericReplayCharSequence.java, InMemoryReplayCharSequence.java
    implement isOpen()
* KeyWordProcessor.java, ExtractorHTML.java, HTTPContentDigest.java,
  ExtractorCSS.java, ExtractorXML.java
    do not close ReplayCharSequence

engine/src/main/java/org/archive/crawler/framework/ToeThread.java

@@ -175,6 +175,7 @@ implements MultiReporter, ProgressStatisticsReporter,
                     // OutOfMemory and any others
                     seriousError(err); 
                 } finally {
+                    httpRecorder.endReplays();
                     KeyedProperties.clearOverridesFrom(curi); 
                 }