Extend tmx canvas size
usage:
In this example.tmx, I manually updated the canvas size (on line 13)
old: <image source="townInterior" width="32" height="18"/>
new: <image source="townInterior" width="64" height="36"/>
Then, the script update all the layers to the new size:
python3 extend-tmx-canvas.py input_file output_file
That's it, all the layers have the new size and the tile data has a bunch of extra zeros. You now have a massive canvas!