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

 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.
Merge commit 'd6e38f24803032ae18cea20490be189230d2a69b' into feature/_internalResolveImage
made style and error handling changes as required
Merge branch 'feature-ide_resolve_image' into release-6.0.1
Minor tweaks to feature-ide_resolve_image.