Add CsvWriterGetWriter
Expose typedef EvalContextEnterpriseState in core
Make promise paths start with slash
Adjust stack path to include namespace, no space before index
Remove dead decls RlistPrintToWriter, RvalPrintToWriter
Add EvalContextStackPromisees

Accumulates all promisees in the stack
Add JsonWriteCompact

For formatting JSON compactly (no pretty printing)
For debug builds, abort() rather than exit(255) in ProgrammingError

Makes it easier to trap my debugger
Add StringSetToJson
Fix const Promise in PromiseActuator warnings in expand_test