Fix compilation under openjdk 1.8.0_60.

diff -up plantuml/src/net/sourceforge/plantuml/AnimatedGifEncoder.java.old plantuml/src/net/sourceforge/plantuml/AnimatedGifEncoder.java
--- plantuml/src/net/sourceforge/plantuml/AnimatedGifEncoder.java.old	2015-06-22 09:50:44.050253313 +0200
+++ plantuml/src/net/sourceforge/plantuml/AnimatedGifEncoder.java	2015-06-22 09:51:08.031355587 +0200
@@ -136,7 +136,6 @@ public class AnimatedGifEncoder {
 	 * 
 	 * @param iter
 	 *            int number of iterations.
-	 * @return
 	 */
 	public void setRepeat(int iter) {
 		if (iter >= 0) {
@@ -258,7 +257,6 @@ public class AnimatedGifEncoder {
 	 * 
 	 * @param quality
 	 *            int greater than 0.
-	 * @return
 	 */
 	public void setQuality(int quality) {
 		if (quality < 1)