[Bleeding] Correct issues with MEGA_REDWOOD trees. Fixes BUKKIT-5568

In commit 6efeddfe57, TALL_REDWOOD was used instead of the proper TreeType
of MEGA_REDWOOD. Additionally, this fixes an issue in CraftWorld with an
improper boolean flag related to the generation of MEGA_REDWOOD trees.

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

@@ -94,7 +94,7 @@ public class BlockSapling extends BlockPlant implements IBlockFragilePlantElemen
             for (i1 = 0; i1 >= -1; --i1) {
                 for (j1 = 0; j1 >= -1; --j1) {
                     if (this.a(world, i + i1, j, k + j1, 1) && this.a(world, i + i1 + 1, j, k + j1, 1) && this.a(world, i + i1, j, k + j1 + 1, 1) && this.a(world, i + i1 + 1, j, k + j1 + 1, 1)) {
-                        treeType = TreeType.TALL_REDWOOD; // CraftBukkit
+                        treeType = TreeType.MEGA_REDWOOD; // CraftBukkit
                         object = new WorldGenMegaTree(false, random.nextBoolean());
                         flag = true;
                         break label78;

src/main/java/org/bukkit/craftbukkit/CraftWorld.java

@@ -393,7 +393,7 @@ public class CraftWorld implements World {
             gen = new WorldGenForestTree(true);
             break;
         case MEGA_REDWOOD:
-            gen = new WorldGenMegaTree(true, rand.nextBoolean());
+            gen = new WorldGenMegaTree(false, rand.nextBoolean());
             break;
         case TALL_BIRCH:
             gen = new WorldGenForest(true, true);