Program Preamble consists of 2 parts: rules & Journal.
Preamble rules are no-input rules with rules for their required nodes.
Preamble journal is journal part with results of executing these rules.
Preamble is defined per-Query, because Journal differs for Queries.
Repository CacheHolder is used for storing them b/w sessions.
Rules are stored and retrievied with Memoizer.
Journal is stored as SessionToken in PreambleSet (map Query->SessionToken).
Add option to IncrementalSpec -- incrementality level (Preamble or Full).