Add Environment Classes for tasks requiring a centralized environment
paradigm (e.g., realtime systems with human feedback or robotics)
Altered Value class to be abstract with specific subclasses for discrete
and real valued instances. This should save memory allocation so that a
discrete and real value does not have to be stored for every value
regardless of type and also open the door to creating new attribute
types.
Added relational attributes/values to support the construction of
relational domains.