inputs/*/maps/src.*.csv: Removed extraneous quotes around fields, which are added by Excel but not by Python

inputs/*/maps/src.*.csv: Removed extraneous quotes around fields, which are added by Excel but not by Python

inputs/CTFS: Added empty maps/src.organisms.csv so that every table of every datasource has a src map

README.TXT: Datasource setup: Documented how to populate the src/ subdir with input data

Added inputs/CVS/

sql_gen.py: plpythonu_error_handler: Translate specific Python exception types to PostgreSQL error codes (ValueError -> data_exception) instead of assuming everything is a data_exception. When removing the PL/Python prefix, preserve the Python exception class in a DETAIL message. Support non-PL/Python internal_errors by re-raising them.

sql_gen.py: Added reraise_exc

schemas/py_functions.sql: _date(): Raise (or pass through) ValueErrors directly instead of wrapping them in FormatExceptions, to simplify the code. This will also enable later translation of ValueErrors to data_exceptions. When year is required and missing, output a parsable 'null value in column year violates not-null constraint' error.

sql_io.py: put_table(): log_exc(): Handle infinite loops from repeated exceptions by removing all rows, instead of just aborting with a failed assertion

sql_io.py: put_table(): is_function: Fixed bug where special case for unrecoverable errors needed to avoid creating an empty output pkeys table because function mode defines the returned pkeys table separately