Document people and related classes

Additions:

• Documentation of all the classes in Model.People
• Documentation of most of the classes in Model.Landscape
• Documentation of all the classes in Model.Common
• Documentation of RollingAggregation
• Tests for VisitableBuilding

Modifications:

• Config and blueprint public variable names to PascalCase
• Closes #85 (closed)

Removals:

• VisitorEffect class. Displaying these three variables required copying them to separate properties, which meant that they were never used together. I've found no reason for keeping this class.
• PavementBlueprint is no longer stored in Pavement (possibly related to #20). This became unnecessary as the garbage can price was made into a property to let the player see it.
• Constructor of WorldEntity with no parameters.