Provides an implementation of McCarthy's `amb` operator with
binding forms and acceptance test operator.

Most functions in reinen-vernunft work off of one or more of the following root
concepts:

- Entity: a hashmap with a :kb/id key mapped to a unique value and namespaced keys
- Table: a set of hashmaps or Entities
- Fact: a vector triple in the form [entity-id attribute value]
- Relation: a set of Facts pertaining to a particular Entity
- LVar: a symbol naming a logic variable that can bind to any value
- Ground: a concrete value
- Query: a set of Facts containing a mix of LVars and Grounds  
- Rules: a set of Facts describing synthetic relations
- Production: a pair of: antecedent query and consequent Facts
- KB: a set of Relations about many Entities and possibly containing Productions  

A minimal implementation of Datalog.

The simplest possible production rules system that uses a set
of EAV tuples as its knowledge base.

A* search implementation.

A simple constraints solver.