Add some more signs to raw sign image.
Rename qsign to sign to reflect generality
Modify tutorial level
Add rainbow art
Add a sphere particle domain, and check domain dimensions

Each domain responds to a dimension() function which returns the amount of
values that the domain generates. For example, spheres are three dimensional
objects because the values that they generate have an x, y, and z coordinate.
When we assign a domain to a particle property, we can make sure that the
dimensions correspond to the type of property it is...
Add finish objects
Add a way to load finish objects in the file
Add a response for our player hitting finish objects depending on what level they're on (this is a hack)
Add finish object to level definition
Clear event manager after level ends
Change rainbow sprite
Add assets for level two