* switch versioning scheme
* switch build system to dune
* sql: EXISTS, nested JOINs, SUBSTRING, DROP VIEW, ALTER RENAME,
RENAME TABLE, DIV, MOD, LAST_INSERT_ID, UNIX_TIMESTAMP(DATE),
TIMESTAMPDIFF, TIMESTAMPADD, DATE, TIME, POW, INSERT DEFAULT
* sql: INSERT scope fixes
* ocaml: monadic IO with `-gen caml_io`
* ocaml: mariadb traits
* ocaml: parameters in callbacks are now named
* sql: variant parameters (ocaml only)
* traits: + Decimal
* typing: rudimentary NULL support
* sql: do not fail on unknown functions (treat as untyped and emit warning)
* gen: allow filtering by DDL, DML, DQL, etc
