Force target paths to lowercase to avoid windows related case-path bugs.

processing.go

@@ -182,7 +182,8 @@ func RenderImages(config Settings, force bool) error {
       }
 
       if force || HasChanged(path_info, target) {
-          JankImage(convert, path, target)
+        // have to lowercase the target path to avoid windows issues
+        JankImage(convert, path, strings.ToLower(target))
       }
     } else {
       fmt.Println("SKIP:", path)