Fix Blender 5.0 compatibility - remove IDProperties from AddonPreferences

[nickvanluyk]

Fixes #1004

Problem

Blender 5.0 removed IDProperties support from AddonPreferences, causing:
TypeError: this type doesn't support IDProperties

Solution

• Removed custom get/set methods (getCacheFolder, setCacheFolder)
• Replaced with standard StringProperty storage
• Added validateCacheFolder() method for validation and folder creation
• Updated register() to validate cache folder on startup

Testing

✅ Tested on Blender 5.0
✅ Maintains backward compatibility
✅ Cache folder setting now works correctly

Files Changed

• prefs.py - Core fix for AddonPreferences compatibility

[domlysz]

Hi thank you ! Reviewed quickly the PR this morning, I dont think it completly replace the originals get/set methods because the new validateCacheFolder method you introduce is called only once (when reading prefs.py) and not every time the cache folder property is reading or writing. Nevertheless, the PR does the job, and the code inside the get/set methods is not crucial, so if will merge it this weekend if I can't find an equivalent with the new API.

[nickvanluyk]

Hi, please do not Merge it yet as i have found a couple issues with this version including what you said and ill try and fix them later today.

[domlysz]

ok I think I found a simple fix 8e5dd39

[nickvanluyk]

This is indeed a way better way of fixing it!
Great work!