Fix region contain method

The region contain method was broken.
A lot of subsquent issues are caused by this bug.
E.g. in a selection the entities in the last blocks at the positive-axis border are not selected.

Max block gives the impression of an exclusive point; however it is inclusive!
A position that is anywhere between of a 1x1x1 region, would return false in the old implementation.

By simply adding a one this should solve the problem.

Greetings

worldedit-core/src/main/java/com/sk89q/worldedit/regions/CuboidRegion.java

@@ -336,9 +336,9 @@ public class CuboidRegion extends AbstractRegion implements FlatRegion {
         Vector min = getMinimumPoint();
         Vector max = getMaximumPoint();
 
-        return x >= min.getBlockX() && x <= max.getBlockX()
+        return x >= min.getBlockX() && x < max.getBlockX() + 1
-                && y >= min.getBlockY() && y <= max.getBlockY()
+                && y >= min.getBlockY() && y < max.getBlockY() + 1
-                && z >= min.getBlockZ() && z <= max.getBlockZ();
+                && z >= min.getBlockZ() && z < max.getBlockZ() + 1;
     }
 
     @Override