make center return boolean if centered. (needed for some moveto operations)

src/main.lua

@@ -293,12 +293,16 @@ local function getnearestunplaced(buf, pbuf, cx,cy,cz,co, sx,sz, setceiling)
     return selected
 end
 local function center(direction, wanted)
-        if direction == 1 and wanted ~= 1 then
-            move("left")
-        end
-        if direction == -1 and wanted ~= -1 then
-            move("right")
-        end
+    if direction == 1 and wanted ~= 1 then
+        move("left")
+        return true
+    end
+    if direction == -1 and wanted ~= -1 then
+        move("right")
+        return true
+    end
+    if direction == 0 then return true end
+    return false
 end
 local function moveto(x,y,cx,cz,direction)
     while x ~= cx or y ~= cz do
@@ -314,16 +318,14 @@ local function moveto(x,y,cx,cz,direction)
         end
 
         if y > cz then -- z
-            center(direction, 1)
+            if center(direction, 1) then move("right") end
             cz = cz + 1
-            move("right")
             move("forward")
             direction = 1
         end
         if y < cz then
-            center(direction, -1)
+            if center(direction, -1) then move("left") end
             cz = cz - 1
-            move("left")
             move("forward")
             direction = -1
         end