Picture for Drag & Drop should not be cached

[sebastianfilke]

• Operating system: All
• Pencil version: 3.0.0-rc.1

if you drag a picture with the same name (for example newPicture.png) again, you get the first instance of this picture (the first drop). it doesn't matter that the picture has changed in the meantime. you have to rename the picture and then you get the changes.