mappings/VegX-VegBIEN.stems.csv: elevation, elevationrange: Added _rangeStart/_rangeEnd filter

sql_io.py: Wrapping mapping in a sql_gen.ColDict: Documented that sql_gen.ColDict sanitizes both keys and values passed into it

sql_gen.py: ColDict: Documented that anything that isn't a column is wrapped in a NamedCol

README.TXT: Datasource setup: Accepting the test cases: Added instructions for what to do if you get errors

bin/map: Fixed bug where needed to use sql.function_exists() to determine if something is a relational (now SQL) function, including in row-based mode, since that now uses sql_io.put_table(), which requires this. The bug fix relies on the new xml_func.process() feature that preserves unknown relational functions in case they are built-in functions rather than SQL functions.

xml_func.py: process(): In row-based mode, when trying to evaluate function using DB, preserve unknown funcs because these might be built-in functions of db_xml.put(). The sql.DoesNotExistException should be raised again when db_xml.put() is run and it verifies whether the function is built-in or not (e.g. _simplifyPath is now built-in, for column-based support). See db_xml.put_special_funcs for built-in functions.

db_xml.py: put(): Fixed bug where strings starting with "$" were interpreted as input columns in row-based mode (this should only apply to column-based mode). Explicitly store whether in row-based mode in is_literals var (similar to is_literals in sql_io.put_table()).

sql_io.py: put_table(): unrecoverable errors: Returning default value: is_literals: Remove column rename from default value so it doesn't get treated as a column by db_xml.put() (which is handled differently from a literal value)

db_xml.py: put(): put_(): Removed no longer needed in_row_ct_ref param, which is only used by put_table(). Rewrapped function body.

sql_io.py: put_table(): ignore(): literals: Only replace invalid literal with NULL or remove row if that column actually contains the invalid value in question. This handles the case where all columns are being ignore()d because the specific column couldn't be identified, and this was not the invalid column.