schemas/vegbien.sql, functions.sql: Made cast functions STRICT to enable the RETURNS NULL ON NULL INPUT optimization

db_xml.py: put_table(): Pass is_func to sql.put_table()

sql.py: put_table(): Added is_func param for whether out_table is the name of a SQL function, not a table

db_xml.py: put_table(): Treat every node name that starts with "_" as a function, not just members of put_table_special_funcs. This ensures that DB function args are always treated as values, not children with fkeys to parent.

bin/map: by_col: Strip only XML functions that are not in the DB

db_xml.py: put_table(): Make special_funcs externally available as module constant put_table_special_funcs

sql.py: tables(): Changed schema param to schema_like and filter the schema using LIKE so that all schemas can be selected

to_do/timeline.doc: Updated to reflect the month we spent on optimization and column-based import

sql.py: put_table(): in_table name: Remove '-pkeys' suffix from the into table name before adding '-input' so that the name is shorter and clearer

sql.py: put_table(): Wrap repr() calls for debug messages in strings.as_tt() to add Redmine formatting