Fixed BUG-11: we have changed to file_refimg_link table (from file_person_link), this means we now have some optimisations, and can definitely re-run AI jobs without crashing. Several optims could still be done - see TODO

TODO

@@ -1,17 +1,11 @@
 ## DB	
-        should FPL really be EPL?
 
-        FILE -> add, has_unidentified_face 
-            ?has_face?, 
-
-        AI_SCAN:
-            id
-            date of scan
-            version of code?
-            settings used
-        AI_SCAN_FILE_LINK
-            id to link to  AI_scan
-            refimg used/found
+    Need to think about...
+        file (image) -> has X faces, Y matches
+            X == Y (optim: dont scan again)
+            say X-Y == 1, then to optimise, we need to only check the missing
+            face... at the moment, the DB structure is not that clever...
+            (file_refimg_link --> file_refimg_link needs a face_num?)
 
 ### BACKEND
     *** Need to use thread-safe sessions per Thread, half-assed version did not work