Limit human entity name length to 16 characters, as per the spec.

src/main/java/net/minecraft/server/EntityTrackerEntry.java

@@ -198,6 +198,11 @@ public class EntityTrackerEntry {
             entityitem.locZ = (double) packet21pickupspawn.d / 32.0D;
             return packet21pickupspawn;
         } else if (this.tracker instanceof EntityPlayer) {
+            // CraftBukkit start - limit name length to 16 characters
+            if (((EntityHuman) this.tracker).name.length() > 16) {
+                ((EntityHuman) this.tracker).name = ((EntityHuman) this.tracker).name.substring(0, 16);
+            }
+            // CraftBukkit end
             return new Packet20NamedEntitySpawn((EntityHuman) this.tracker);
         } else {
             if (this.tracker instanceof EntityMinecart) {