Make //count take a mask. Also doc updates, perm fixes.

worldedit-core/src/main/java/com/sk89q/worldedit/command/RegionCommands.java

@@ -374,7 +374,7 @@ public class RegionCommands {
         desc = "Deforms a selected region with an expression",
         descFooter = "The expression is executed for each block and is expected\n" +
             "to modify the variables x, y and z to point to a new block\n" +
-            "to fetch. See also tinyurl.com/wesyntax."
+            "to fetch. See also https://tinyurl.com/weexpr"
     )
     @CommandPermissions("worldedit.region.deform")
     @Logging(ALL)