Fix some javadoc 8 errors in libs

This fixes the errors in the libraries that opsu uses that
the new html linter in the Java 8 javadoc tool catches and
classifies as error.

Whether or not this should be merged or whether this should
be fixed upstream first is for someone else to decide :P

src/org/newdawn/slick/GameContainer.java

@@ -555,8 +555,8 @@ public abstract class GameContainer implements GUIContext {
 	 * bottom.
 	 * 
 	 * @param ref The reference to the image to be loaded
-	 * @param x The x-coordinate of the cursor hotspot (left -> right)
-	 * @param y The y-coordinate of the cursor hotspot (bottom -> top)
+	 * @param x The x-coordinate of the cursor hotspot (left {@literal ->} right)
+	 * @param y The y-coordinate of the cursor hotspot (bottom {@literal ->} top)
 	 * @param width The x width of the cursor
 	 * @param height The y height of the cursor
 	 * @param cursorDelays image delays between changing frames in animation

src/org/newdawn/slick/Image.java

@@ -935,7 +935,7 @@ public class Image implements Renderable {
 	
     /**
      * Set the angle to rotate this image to.  The angle will be normalized to 
-     * be 0 <= angle < 360.  The image will be rotated around its center.
+     * be {@literal 0 <= angle < 360}.  The image will be rotated around its center.
      * 
      * @param angle The angle to be set
      */
@@ -973,7 +973,7 @@ public class Image implements Renderable {
     
     /**
      * Add the angle provided to the current rotation.  The angle will be normalized to 
-     * be 0 <= angle < 360.  The image will be rotated around its center.
+     * be {@literal 0 <= angle < 360}.  The image will be rotated around its center.
      *  
      * @param angle The angle to add.
      */

src/org/newdawn/slick/Music.java

@@ -42,7 +42,7 @@ import org.newdawn.slick.util.Log;
  * play at any given time and a channel is reserved so music will always play. 
  *
  * @author kevin
- * @author Nathan Sweet <misc@n4te.com>
+ * @author Nathan Sweet {@literal <misc@n4te.com>}
  */
 @SuppressWarnings({"rawtypes", "unchecked"})
 public class Music {

src/org/newdawn/slick/openal/OpenALStreamPlayer.java

@@ -46,7 +46,7 @@ import org.newdawn.slick.util.ResourceLoader;
  * as required.
  * 
  * @author Kevin Glass
- * @author Nathan Sweet <misc@n4te.com>
+ * @author Nathan Sweet  {@literal <misc@n4te.com>}
  * @author Rockstar play and setPosition cleanup 
  */
 public class OpenALStreamPlayer {