ImageToolkit annotation object left under system module

We should at least adapt the existing implementations as well. They work because we now have magic loading of annotations.

If you apply the patch there is still some use Drupal\system\Annotation\ImageToolkit;statements in core.

I did a global search on " extends plugin" to find all annotation classes. They are always in an Annotation subdirectory. Most of the times they are under an Annotation subdirectory of the directooy where the plugin type itself can be found. The only exception is Action which is directly under /Core/Annotation instead of /Core/Action/Annotation.

So the file should be moved to Core\ImageToolkit\Annotation. and the namespace should be adapted accordingly.

Under Annotation/ makes it more understandable, I believe.

Grepped the codebase after applying #8:

• no more uses of the annotation class in the toolkit plugins (3 of them, GDToolkit, TestToolkit and BrokenToolkit)
• no more API files under the system module, just the GDToolkit plugin implementation

RTBC

Committed and pushed to 8.x. Thanks!