[GREENFOOT-191] Error when setting image for an Actor (windows only)

greenfoot 1.4.5 on windows does not create the image directory in new projects, which means that an error is thrown when the user tries to create a new actor and set the image for it.

This also happens if the image dir is deleted extrenally for some reason.

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Issue metadata

• Issue type: Bug
• Priority: High
• Fix versions: 1.4.6