added _internal resolve image [id] <id or name> relative to <object ref>


This command resolves a short id or name of an image as would be used for an icon
 and sets `it` to the long ID of the image according to the documented rules for resolving
 icons.

`it` is set empty if the command fails to resolve the image which means it's not on any stack in memory.

Syntax example:
````
_internal resolve image id the icon of button X relative to button X
if it is not empty then
   -- copy it to standalone
end if
````