Nodered.py

- remove "default_category_visible" parameter from RED.
- update "REDBuilder".
- add "default_categories" parameter to RED.
- update "REDBuilder".
- add "PropertyDivider" property.
- generates horizontal line in Node-RED editor dialog.
- add lint text to REDBuilder.
- update "README.md"

- remove "pandas" from requirements.
- fix bugs.
- error in route mapping.
- separate "red", "node", "route" from "__init__".
- update related files.
- add exception handle to route.
- if error, error message from traceback will return.
- add "display_name" to property.
- add lint text to property classes.

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- add "route", "static" functions.
- route is function to register http endpoint to express.js
- static is function to register static endpoint to express.js
- register favicon to express.js server.
- use "editor_theme.page.favicon" file.
- update "README.md"
- update tests.

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- change package from legacy(setup.py) to flit.
- hide "nodered", "property" from hirarchy.
- change "editor_theme", "auths" to class.
- update "README.md"

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- bug fixes.
- "ComboBoxProperty" value not updated.
- if default value is None, no erros more.
- use required property.
- change var names(for freedom of name selection).

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- add "node_root", "enable_remote_access" to "RED" init.
- raise error when "admin_root" and "node_root" not start with "/".
- fix some code.

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