- Change some command names for more consistency
- Better handling of errors and exception in all show* commands.
- Add all show_*_catalog commands
- Add show_backup_job_details command
- Use prettytable module to format the output for show_* commands.
- Delete all pl/pgsql function used to create output for show_* commands.
  They did not scale and the performance was not good.
- Change some ID columns names in the database for more consistency.