schemas/vegbien.sql: party: Changed indexes to use `COALESCE` to match what sql_gen now does

Wrap sys.stderr.write() calls in strings.to_raw_str() to avoid UnicodeEncodeErrors when stderr is to a file and the default encoding is ASCII

strings.py: Added to_raw_str()

bin/map: When logging the row # being processed, add 1 because row # is interally 0-based, but 1-based to the user

bin/map: Log the row # being processed with level=1.1 so that the user can see a status report if desired

exc.py: str_(): Fixed bug where UnicodeEncodeError would be raised when msg contains non-ASCII chars, by wrapping e.args⁰ in strings.ustr()

exc.py: print_ex(): Wrap msg in strings.to_unicode() to try to avoid UnicodeEncodeError when msg contains non-ASCII chars

sql.py: create_table(): Don't set pkey.nullable to False because the caller should make sure the pkey has the appropriate type

csv2db: Use sql_gen.TypedCol.nullable instead of manually adding 'NOT NULL' to the type. Ensure that pkeys are properly NOT NULL.

csv2db: Adding indexes: Create plain indexes using ensure_not_null=False because the indexes will primarily be used by the user to search for specific values, rather than by the mapping script which uses the ensure_not_null