Campaign screening scalars / CON ingest contracts for corpus stores (readcon-db).
Campaign-store index projection: screening scalars and contracts derived from
a parsed ConFrame so corpora (e.g. readcon-db) do not
fork CON semantics.
Minor implemented by this reader. Newer minors of major 3 are accepted.
An unknown section is skipped only when the frame minor is greater than
this value and section_arity gives the value-field count
(CON-section.8, CON-section.12, D14).