Pyrseas

Convert Pyrseas to use Psycopg version 3. Remove support for Python
2.x and Postgres versions prior to PG 10.

Reinstate code for interfacing with psycopg, removing the dependency
on pgdbconn.

Fixed various issues, including:

* Partial fix for database objects owned by extensions. (236)

* Deal with pg_pltemplate catalog being removed in PG 13. (226, 227)

* Problem with trigger procedures with arguments. (219)

Expanded the number of keywords that are quoted if they are present in
generated SQL statements. (212)

Various changes to support Postgres 12.

Fixed various issues, including:

* Handling of multiple foreign key constraints (210)

* Column qualifications in Extensions query (208)

Schema 'public' is no longer treated as a special case (176)

Yamltodb was changed to support Postgres 11, in particular due
to changes to the 'pg_proc' catalog (195)

Dbtoyaml now outputs column information for views, both regular and
materialized (184)

Fixed various issues, including:

* Do not assume constraints always refer to columns (188)

* Add non-'public' schemas to search_path to avoid problems with
some extensions (e.g., PostGIS) that need them to resolve
objects (91)

* Prevent a view definition from changing a column type (90)

* Inconsistent handling of FOREIGN KEY and UNIQUE constraints
leading to AttributeErrors (182)

* Recreation of tsvector triggers when columns are added (179)

Significant rearchitecture of methods to generate SQL.

* An object dependency graph is built and traversed to generate SQL
in correct order (72, 86, 100)

Added support for Postgres 10, specifically:

* Table partitioning syntax (163)

* Column specification GENERATED AS IDENTITY (164)

Added support for other Postgres features:

* Parallel safe functions and partial aggregation (161)

* RANGE types (173)

* ALTER TYPE ADD VALUE for changes to ENUM types (87)

Fixed various issues, including:

* Do not error on tables whose names start with 'public' (109)

* Deal properly with inherited constraints in children tables (102)

* Handle external languages like plv8 correctly (97)

* Correct quoting of mixed case constraint names (83)

* Avoid problems with certain complex index definitions (98)

* Have dbtoyaml output correctly a table with an embedded period in
the name and having an associated sequence (79)

* Use relative paths in database summary for ``--multiple-files``
(93)

* Support mapping of indexes on materialized views (82)

* Moved ``config.yaml`` under ``pyrseas`` directory and use
``package_data`` to install (77)

* yamltodb output to a file is encoded using utf-8 (78)