[request] IDE: normalize indentation according to preference settings when loading a script

[RaiMan]

This request is based on the linked question.

**** problem description / workaround

-indentation tabs are not handled at the time a script is loaded into the IDE, only when editing a script in the IDE. Or more generally: when loading a script, indentation is not normalized according to the current settings in the IDE's preferences.

- So you might come up, with a situation, that a loaded script does not conform to the current tab settings and things get messed up, when you start editing.

- A workaround would be, to change all tabs to the required spaces in a capable editor directly in the .py files with search-and-replace before loading the script into the IDE

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So when loading a script, the user should get a warning, when the script's indentation does not conform to the current settings.

Options to be implemented and presented together with the warning:
- change preferences according to script's situation
- change script's indentation according to the preferences
- switch off indentation support for this script