+=
changed (corrected) semantics of isTruthy/isFalsy (~= isRef/isNonRef)
abstLattice2 with NumStr; new benv lookup with 'found' flag
fixed (hacked) l.add
pushdown v2 based on forward reachability in loops
added back marks, all green
removed UpdateIdentifierKont; removed unch transition in
evalStatementList
AtomicEvaluator; improved ToString(); fixed doProtoLookup;