sql_gen.py: esc_name(): If is_safe_name(), just return name, to avoid escessive escaping in debug output for Redmine

sql_gen.py: is_safe_name(): Don't consider uppercase letters safe because they would cause inconsistent behavior in PostgreSQL if quoted vs. not quoted (only unquoted identifiers are case-insensitive)

sql.py: Removed no longer needed check_name()

sql.py: esc_name_by_module(): psycopg2: If ignore_case is set but name is unsafe, just escape it instead of raising an exception

sql_gen.py: Added is_safe_name()

sql.py: put_table(): col_ustr(): Removed no longer needed sql_gen.as_Col() because mapping and join_cols now ensure that their contents are sql_gen.Col objects

schemas/functions.sql: Added _alt relational function

sql.py: put_table(): Make mapping and join_cols a sql_gen.ColDict so that literal values will always be turned into sql_gen.Col objects. DuplicateKeyException: Use dict_subset_right_join() instead of dict_subset() so that all columns in a constraint are included in joins on out_table (such as for a relational function with omitted arguments).

sql_gen.py: Added ColDict

sql_gen.py: as_Col(): Added optional name param to specify that non-Col input will be renamed using NamedCol with the given name