make every conversation's calculations reproducible to the app author

[simonpcouch]

Halfway there would be inlining the database connection code and then interleaving run_sql() calls as dbExecute() and run_r() as normal R code in a .R file.

The proper treatment might use ir based on the active connect deployment and intelligently resolve viewer-based credentials. That still doesn't account for changes in the queried database, though.