forward port of double-thumbnail bug. Image was inheriting a Storage object from File, and needed a Storage::Image object

docs/changelog/7.x.x.txt

@@ -59,6 +59,8 @@
     http://www.webgui.org/bugs/tracker/activity-sequence-numbers-incorrect-when-editing-workflows#YRH7TYSWFkEUSPVDNN6zKQ
  - fix: Spectre Should Check That It Has a Valid Workflow (perlDreamer Consulting, LLC)
     http://www.webgui.org/bugs/tracker/spectre-should-check-that-it-has-a-valid-workflow#lHx4BxEUxcacX7rS5VLxeg
+ - fix: Problems with thumbnails (perlDreamer Consulting, LLC)
+    http://www.webgui.org/bugs/tracker/problems-with-thumbnails
 
 
 7.3.18

docs/gotcha.txt

@@ -7,7 +7,6 @@ upgrading from one version to the next, or even between multiple
 versions. Be sure to heed the warnings contained herein as they will
 save you many hours of grief.
 
-
 7.4.0
 --------------------------------------------------------------------
 
@@ -31,6 +30,17 @@ save you many hours of grief.
    the upgrade
 
 
+7.3.19
+--------------------------------------------------------------------
+
+ * There was a bug fixed in this release relating to the Image asset.
+   The bug was that if you edited an Image, then the original image file
+   in the asset was replaced with its thumbnail.  There is no easy way to
+   automatically fix this the results of this bug.  To recover affected
+   Image Assets, then just upload a copy of the original image file.  You
+   do not need to Trash/Delete the Image Asset.
+
+
 7.3.16
 --------------------------------------------------------------------