Implementation of the structure: gzz.impl

The most important new architectural feature in version 0.8 is ModularSpace: the responsibilities of the Space object are split among several small objects, each one much more cohesive than the previous implementations of space, and decoupled from one another.

Of course, this makes the inheritance hierarchy slightly more complex; although not impossibly so. Since the classes have clearly defined responsibilities, this is not really a problem. The following class diagram shows ModularSpace and the associated classes: