Restore option to replace sprite using the most recent image file

[morganwillcock]

Describe the problem

When the updated sprite importing was added it removed the option to replace a sprite using the most recently used image file.

Now there is not an equivalent function that can be used to repeatedly replace the sprite images from a common spritesheet file.

There is not a workaround using image export because this produces individual images rather than restoring a spritesheet which can be edited as if it were the original spritesheet.

Discussed here in full here:
https://www.adventuregamestudio.co.uk/forums/index.php?msg=636653195

Suggested change

Restore the removed menu option, using the first (or last, it might depend on how the option is named) image from the previous set of images which were used.

The tracking of previously used files would probably need to be changed. I think at the moment it is just remembering the files used for a brand new import and doesn't consider files used to replace the image on an exsiting sprite.