Delete calculated images when replacing image file

[luya-bot]

This issue has originally been reported by @rolandschaub at luyadev/luya#1701.
Moved here by @nadar.

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What steps will reproduce the problem?

Replace an image file with a new file using the "Replace" button in the file manager.

What is the expected result?

The new image should be displayed in the administration (e.g. in blocks) and frontend.

What do you get instead? (A Screenshot can help us a lot!)

The image is missing in the administration and frontend (LUYA is reporting that the original file is missing). When reselecting the image in a block, the old version is displayed again.

Additional infos

| LUYA Version | dev master

[nadar]

Should be fixed with new file manager.