include and translate texture slots during copy&paste

When blocks of map geometry are copy-pasted between maps (or xmaps), this
commit translates the texture slot numbers between different texture
config sets. Missing textures are assigned a slot in the target map.

When texture slots are added, automapconfig gets enabled.

If the paste gets removed by the undo function, the newly assigned texture
slots will NOT be removed. This is by design.

source/src/worldlight.cpp

@@ -360,7 +360,23 @@ block *blockcopy(const block &s)
     return b;
 }
 
-void blockpaste(const block &b, int bx, int by, bool light)  // slow version, editmode only
+void blocktexusage(const block &b, uchar *used)
+{
+    const sqr *q = (const sqr *)((&b)+1);
+    loopirev(b.xs * b.ys)
+    { // collect used texture slots in block
+        used[q->wtex] = 1;
+        if(q->type != SOLID)
+        {
+            used[q->ctex] = 1;
+            used[q->ftex] = 1;
+            used[q->utex] = 1;
+        }
+        q++;
+    }
+}
+
+void blockpaste(const block &b, int bx, int by, bool light, uchar *texmap)  // slow version, editmode only
 {
     const sqr *q = (const sqr *)((&b)+1);
     sqr *dest = 0;
@@ -376,7 +392,15 @@ void blockpaste(const block &b, int bx, int by, bool light)  // slow version, ed
         tg = dest->g;
         tb = dest->b;
 
-        *dest = *q++;
+        *dest = *q;
+
+        if(texmap)
+        { // translate texture slot numbers
+            dest->wtex = texmap[q->wtex];
+            dest->ctex = texmap[q->ctex];
+            dest->ftex = texmap[q->ftex];
+            dest->utex = texmap[q->utex];
+        }
 
         if (light) //edit mode paste
         {
@@ -384,6 +408,7 @@ void blockpaste(const block &b, int bx, int by, bool light)  // slow version, ed
             dest->g = tg;
             dest->b = tb;
         }
+        q++;
     }
     block bb = { bx, by, b.xs, b.ys };
     remipmore(bb);