get rid of unused .empty_directory files in the app generator
Merge pull request #8754 from amatsuda/app_generator_unused_empty_directories

get rid of unused .empty_directory files in the app generator
misleading error message that prompts non-existing command

[ci skip]
Merge pull request #8758 from amatsuda/plugin_new_error_message

Misleading error message that prompts non-existing command [ci skip]
Support for PostgreSQL's ltree data type.