Implemented snapshot support for 1.2.

By: Mike Primm <mike@primmhome.com>

paper-api/src/main/java/org/bukkit/ChunkSnapshot.java

@@ -111,4 +111,11 @@ public interface ChunkSnapshot {
      * @return time in ticks
      */
     long getCaptureFullTime();
+
+    /**
+     * Test if section is empty
+     * @param sy - section Y coordinate (block Y / 16)
+     * @return true if empty, false if not
+     */
+    boolean isSectionEmpty(int sy);
 }