Refactor extractor

- Refactor info classes and extractors
- Reformat and fix indentation
- Organize packages and classes
- Rename variables/methods and fix regex
- Change the capitalization
- Add methods to playlist extractor

Info.java

@@ -0,0 +1,19 @@
+package org.schabi.newpipe.extractor;
+
+import java.io.Serializable;
+import java.util.List;
+import java.util.Vector;
+
+public abstract class Info implements Serializable {
+
+    public int service_id = -1;
+    /**
+     * Id of this Info object <br>
+     * e.g. Youtube:  https://www.youtube.com/watch?v=RER5qCTzZ7     >    RER5qCTzZ7
+     */
+    public String id = "";
+    public String url = "";
+    public String name = "";
+
+    public List<Throwable> errors = new Vector<>();
+}