Split out abstract syntax
Split out substitution
Delete obsolete implicit substitution model
Split out denotational semantics
Split out operational semantics
Split out generic parsing
Split out data encoding
Split out syntax-0 parsing
Split out syntax-0 unparsing
Split out interaction
Split out syntax-1 bootstrapping
Split out syntax-1 parsing
Eliminate unnecessary imports
Rename base.rkt to syntax-1.rkt
Fix run.rkt