Add text to say you've died
Reset the level when you restart it.

I've separated the initialisation code from the creation code to do this. Also
restructured things a bit: now there's a separate Scene per level (or would be
if we had more than one level) and we look up the references to objects inside
it when we switch to the level.
Update some comments
Trying to add a results screen
Add a 'level complete' state
Add a tool to generate levels from images.

It reads TGA files and produces levels in JSON format.
Add more things to the fix_perms target
Bug fixes and better error reporting for the levelgen tool
Final check-in before submitting.