Port to XC.

Or try; still need to test.
Use one SQL file for Postgres and XC.

Just specify table options as a plsql variable to set the distribution option.
Fix test failures on Win32.
Note PGXC support.
Note XC distribution by replication.
add checks for MariaDB
Simplify Maria DB detection, give @edlitmus credit.
Detect XC on the server, instead of the client.

This would allow one to deploy to a remote XC server using non-XC psql.
Use probe instead of capture.
Note XC and MariaDB support in engines.
Mention XC and Maria in the main doc and the config doc.
Spelling.
Upcate copyright date.
Update language catalogs.
Timestamp v0.992.
Increment to v0.993.
Add v0.993 to Changes.
Merge remote-tracking branch 'upstream/master'