New Feature: static fortifications can now be built by mercs (by Flugente)

- if the terrain allows it, an empty sandbag (item 1540) can be filled to a full sandbag (item 1541). You need to have a shovel (item 1015) in your second hand. You will notice the new hammer cursor
- by using a full sandbag, you can build a sandbag barrier
- by using a concertina stack, you can build a concertina wire barrier
- this only works if the current map has sandbags/concertina wire in its tileset
- with a shovel in your hand, you can remove a sandbag barrier
- changed the size of shovel so it can actually be put in inventories. It was also necessary to remove its ability to be used as a melee weapon.
- for further info, see this thread: http://www.bears-pit.com/board/ubbthreads.php/topics/305822.html#Post305822


git-svn-id: https://ja2svn.mooo.com/source/ja2/trunk/GameSource/ja2_v1.13/Build@5340 3b4a5df2-a311-0410-b5c6-a8a6f20db521

Tactical/Structure Wrap.cpp

@@ -564,6 +564,22 @@ BOOLEAN IsRefuelableStructAtGridNo( INT32 sGridNo, UINT8 *pubID )
 }
 
 
+// Flugente: determine wether a fortification can be built on this position
+BOOLEAN IsFortificationPossibleAtGridNo( INT32 sGridNo, UINT8 *pubID )
+{
+	GetMouseMapPos( &sGridNo );
+		
+	INT8 bOverTerrainType = GetTerrainType( sGridNo );
+	if( bOverTerrainType == MED_WATER || bOverTerrainType == DEEP_WATER || bOverTerrainType == LOW_WATER )
+		return FALSE;
+
+	STRUCTURE * pStructure = NULL;
+
+	pStructure = FindStructure( sGridNo, (STRUCTURE_OBSTACLE) );
+
+	return( pStructure == NULL );
+}
+
 
 BOOLEAN IsCutWireFenceAtGridNo( INT32 sGridNo )
 {