-map changes during game don't affect map itself

mapa.lua

@@ -1,6 +1,24 @@
 --mapa={}
 tiletype={void=0,stair=1,switch=2,half=3,block=4}
 
+function mapa_do_backup()
+    mapa_backup={}
+    for i=1,#mapa do
+        mapa_backup[i]={}
+        for j=1,#mapa[i] do
+            mapa_backup[i][j]=mapa[i][j]
+        end
+    end
+end
+
+function mapa_restore_backup()
+    for i=1,#mapa do
+        for j=1,#mapa[i] do
+            mapa[i][j]=mapa_backup[i][j]
+        end
+    end
+end
+
 function mapa_new()
     for my=0,7 do
         for mx=0,9 do