Announce pgcat

Hi All,

Here I announce the pgcat project: Enhanced postgresql logical replication.

The built-in logicial replication has below shortages:

* only support base table as replication target
* do not filter any origin, which will cause bi-directional dead loop
* could not do table name mapping
* no conflict resolution

pgcat makes below enhancements:

* supports any table type as replication target
e.g. view, fdw, partitioned table, citus distributed table
* only replicates local changes
so that you could make bi-directional replication,
e.g. replicates data between two datacenter
* table name mapping
* optional lww (last-writer-win) conflict resolution
* save replication progress in table, so that it would be logged
when subscriber failovers, it would retain the progress. In contrast,
the built-in logical replication of pg saves the progress in non-logged file.

Please check https://github.com/kingluo/pgcat for more detail.

Thanks!

Regards,
Jinhua Luo