saveRoi: Renamed a local variable
Renamed `texturesx` to `textures`.
Removed obsolete function `OutputTile`
Use class `TileCombiner` instead of function `saveTiles`
Benefit: No need to keep all the tiles in memory at once.
Appends a tile to the OBJ file as soon as the tile is obtained.
saveRoi: Added debug output
Prints number of tiles to be processed.
Minor reformat (removed a blank line)