sql_io.py: put_table(): Removed into param to set a custom into table name because put_table() now has all the info it needs to generate this name automatically, and callers are no longer providing it

bin/map: by_col: db_xml.put_table() call: Use new col_defaults param to automatically set datasource_id to the in_label (datasource name)

xpath.py: path2xml(): Skip to tree created inside root, since that is how callers want to use the returned node

db_xml.py: put_table(): Import col_defaults to translate nodes to pkeys

db_xml.py: _put_table_part(): Support no in_table, for iterations with only literal values

sql_io.py: put_table(): is_literals: When ignoring all rows, return default value instead of always None

db_xml.py: put_table(): Removed parent_ids_loc and next params since these are only used in the recursion

db_xml.py: put_table(): Split into an outer function that sets up the database environment and subsets in_table, and a (recursive) inner function that imports the data

db_xml.py: put_table(): Subsetting and partitioning in_table: Documented that it's OK to do this even if table already the right size because it takes <1 sec

sql_io.py: put_table(): Use is_function where caller-provided is_func was used, since is_function determines whether something is a function based on whether it actually exists as a SQL function instead of just whether its name starts with "_". Removed now-unneeded is_func param.