schemas/util.sql: added derived_cols(), which gets table_'s derived columns (all the columns not in the names table)

schemas/util.sql: added eval2set()

schemas/util.sql: added drop_column()

inputs/REMIB/Specimen/postprocess.sql: map_nulls__*(): turned off STRICT to allow dynamic inlining, which speeds up the mk_derived_col() statements by 5x (342799.823 ms -> 71533.252 ms (6 min -> 1 min) for latitude_sec)

inputs/REMIB/Specimen/postprocess.sql: runtimes: updated for vegbiendev, before dynamic inlining. the times are about twice as fast as on starscream, so vegbiendev is faster at whatever is the limiting speed factor (probably not CPU, based on other benchmarks).

schemas/util.sql: map_nulls(): documented that due to dynamic inlining, this is just as fast as util._map() which it wraps. dynamic inlining now brings altogether a 40x speed improvement to map_nulls() (4000 ms -> 100 ms), and would likely bring a comparable improvement for other functions that are run repeatedly and call other user-defined functions.

bugfix: schemas/util.sql: map_nulls(): updated to use hstore(text[], anyelement), which has replaced hstore(anyarray, anyelement)

schemas/util.sql: removed hstore(anyarray, anyelement), which did not support dynamic inlining, to avoid confusion over which hstore() function to use. use new hstore(text[], anyelement) instead (with explicit cast on the keys array if needed).

schemas/util.sql: added hstore(text[], anyelement), which dynamically inlines properly, unlike hstore(anyarray, anyelement). this can be selected by explicitly casting the keys array to text[], which now provides a 6x speed improvement (380 ms -> 60 ms) for map_nulls().

schemas/util.sql: fix_array(): turned off STRICT to allow dynamic inlining, which speeds up util.map_nulls() by 3x (1500 ms -> 500 ms)