bugfix: inputs/input.Makefile: `%/install: %/create.sql`: don't include %/header.csv as a target, so that it won't get deleted if the install fails (especially on a step that happens after the header is exported)

inputs/VegBank/taxonobservation_/postprocess.sql: added primary key. note that the inserted row count changes, most likely because the rows are now in sorted order.

inputs/VegBank/stemcount_/postprocess.sql: added primary key. note that the inserted row count changes, most likely because the rows are now in sorted order.

bugfix: schemas/util.sql: mk_subset_by_row_num_func(): need explicit ORDER BY on the row_num_col, to prevent PostgreSQL from sorting the rows in reverse (they will be sorted because of the index scan, but the direction is otherwise indeterminate)

schemas/util.sql: mk_subset_by_row_num_func(): support tables whose pkeys don't start with 1 (such as the VegBank tables), by calculating the smallest row_num from the table

schemas/util.sql: offset2row_num(), limit2row_num(): added optional min_row_num, for tables whose serial pkeys start from a value other than 1

schemas/util.sql: added qual_name(regclass)

schemas/util.sql: added esc_name__append()

schemas/util.sql: added col__min()

schemas/util.sql: added limit2row_num() and use it in mk_subset_by_row_num_func() for clarity