Re-allow INDEX_VAR as rt_index in ChangeVarNodes().

Fix thinkos in have_unsafe_outer_join_ref; reduce to Assert check.

Invent "join domains" to replace the below_outer_join hack.

Do assorted mop-up in the planner.

Make Vars be outer-join-aware.

Avoid copying undefined data in _readA_Const().

Implement WRITE_READ_PARSE_PLAN_TREES for raw parse trees

Enable WRITE_READ_PARSE_PLAN_TREES of rewritten utility statements

Don't lose precision for float fields of Nodes.

Fix write/read of empty string fields in Nodes.

Remove test_oat_hooks.c's nodetag_to_string().

Add a regression test for contrib/tcn.