ADD basic playlist support + youtube playlist support

playlist/PlayListInfoItemCollector.java

@@ -0,0 +1,33 @@
+package org.schabi.newpipe.extractor.playlist;
+
+import org.schabi.newpipe.extractor.InfoItemCollector;
+import org.schabi.newpipe.extractor.channel.ChannelInfoItemExtractor;
+import org.schabi.newpipe.extractor.exceptions.ParsingException;
+
+public class PlayListInfoItemCollector extends InfoItemCollector {
+    public PlayListInfoItemCollector(int serviceId) {
+        super(serviceId);
+    }
+
+    public PlayListInfoItem extract(PlayListInfoItemExtractor extractor) throws ParsingException {
+        final PlayListInfoItem resultItem = new PlayListInfoItem();
+
+        resultItem.name = extractor.getPlayListName();
+        resultItem.serviceId = getServiceId();
+        resultItem.webPageUrl = extractor.getWebPageUrl();
+        try {
+            resultItem.thumbnailUrl = extractor.getThumbnailUrl();
+        } catch (Exception e) {
+            addError(e);
+        }
+        return resultItem;
+    }
+
+    public void commit(PlayListInfoItemExtractor extractor) throws ParsingException {
+        try {
+            addItem(extract(extractor));
+        } catch (Exception e) {
+            addError(e);
+        }
+    }
+}