Number entries on publish, delete media, read the cover

- drafts stay unnumbered, the number is handed out when an entry goes live
- DELETE /api/v1/media/:id and a delete control in the media library
- cover_media_id in the draft read, coverMediaId and coverUrl in the archive read

messages/en.json

@@ -703,7 +703,10 @@
 		"card": {
 			"meta": "{width} × {height} · {size} KB · {variants, plural, =0 {no rendition} one {# rendition} other {# renditions}}",
 			"altMissing": "No alt text. It is mandatory for public entries.",
-			"variantError": "The renditions could not be created. The original is stored and usable."
+			"variantError": "The renditions could not be created. The original is stored and usable.",
+			"delete": "Delete image",
+			"deleteConfirm": "Really delete?",
+			"keep": "Keep"
 		},
 		"messages": {
 			"uploaded": "The image is uploaded and the renditions are created.",
@@ -714,7 +717,9 @@
 			"unreadableImage": "The file cannot be read as an image. Check whether it is complete.",
 			"projectUnknown": "This project does not exist.",
 			"mediaUnknown": "This image no longer exists.",
-			"uploadFailed": "Uploading did not work just now. Try again in a moment."
+			"uploadFailed": "Uploading did not work just now. Try again in a moment.",
+			"deleted": "The image is deleted.",
+			"mediaInUse": "The image is still used in an entry. Remove it there first."
 		}
 	},
 	"mail": {