(svn r3695) Add 2 MarkTileByTile() which I forgot in r3689 (noticed by Belugas)
/* $Id$ */
static inline void MakeVoid(TileIndex t)
{
SetTileType(t, MP_VOID);
SetTileHeight(t, 0);
_m[t].m1 = 0;
_m[t].m2 = 0;
_m[t].m3 = 0;
_m[t].m4 = 0;
_m[t].m5 = 0;
_m[t].extra = 0;
}