sql.py: mk_select(): conds: Support containers of any iterable type

sql.py: put_table(): Made conds a list so that there can be multiple conditions on the same column

sql.py: mk_select(): conds is list of (key, value) tuples instead of dict (dict still supported for compatibility), so that there can be multiple conditions on the same column

sql.py: mk_select(): conds is list of (key, value) tuples instead of dict (dict still supported for compatibility), so that there can be multiple conditions on the same column

util.py: NamedTuple inherits from objects.BasicObject so that it's comparable and hashable. This fixes a bug in dicts.make_hashable() where the NamedTuple created for a dict would appear to be hashable but would always compare as unequal.

sql.py: DbConn.esc_value(): Run strings.to_unicode() on the generated string so that if it contains unescaped non-ASCII characters, these will not cause problems when concatenated with plain strings

sql.py: run_query(): FunctionValueException: Unpack match.groups() into vars to make code clearer

exc.py: str_(): Avoid traceback exception-formatting functions when possible because they escape non-ASCII characters

sql.py: get_cur_query(): If no raw query: Use strings.ustr() instead of repr() to ensure that if the exception is parsed, embedded quotes will not be double-escaped. Prefix the query by [input] to show that it's not the raw query.

sql_gen.py: Non-Code objects: str() passes informative placeholder string to self.to_str() instead of empty string