sql_io.py: put_table(): Removed no longer used conds var (invalid rows are removed from the in_table using sql.delete() instead of being filtered out in the main select)

sql_io.py: put_table(): Removed no longer used distinct_on var (sql.distinct_table() handles filtering the join_cols)

schemas/py_functions.sql: _date(): Just run str() on the returned datetime because it will usually be converted to a PostgreSQL timestamp anyway, so excluding the time from the string isn't necessary

schemas/py_functions.sql: Added _date()

sql.py: run_query(): Exception parsing: Remove PL/Python prefix from exception message so that the regexps can match at the beginning of the message

sql_io.py: put_table(): Handle sql.InvalidValueExceptions by filtering the value out of all input columns. This will be useful for SQL functions that raise exceptions.

schemas/vegbien.sql: namedplace, plantname: *_unique UNIQUE INDEX: Reordered columns to put rank after parent_id and plantname so that these columns, which are usually input table columns, can be used in a merge join index scan, while rank, which is usually a literal value, can applied as an index filter condition after the merge join

sql.py: distinct_table(): Removed literal values from UNIQUE INDEXes because the query planner did not seem to use them to do a merge join

README.TXT: Maintenance: Full DB: Documented how to test full DB backup

backups/Makefile: Added %.backup/test