Fix: Reset the state variables at the end

Also update the casing of publishdate and expirydate to publishDate
and expiryDate to match with the documentation on
https://gohugo.io/content-management/front-matter/#front-matter-variables. The
case of the front matter variables does not matter, but still.. just
for consistency.

example-site/content/singles/post-draft.md

@@ -1,11 +1,11 @@
 +++
 title = "Single Post, but draft"
 date = 2017-07-20
+publishDate = "2017-07-22"
+expiryDate = "2017-07-23"
 tags = ["single", "toml"]
 categories = ["cat1", "cat2"]
 draft = true
-publishdate = 2017-07-22
-expirydate = 2017-07-23
 [menu.foo]
   parent = "main"
   weight = 10

example-site/content/singles/post-toml.md

@@ -1,10 +1,10 @@
 +++
 title = "Single Post with TOML front matter"
 date = 2017-07-20
+publishDate = "2017-07-22"
+expiryDate = "2017-07-23"
 tags = ["single", "toml"]
 categories = ["cat1", "cat2"]
-publishdate = 2017-07-22
-expirydate = 2017-07-23
 [menu.foo]
   parent = "main"
   weight = 10

example-site/content/singles/post-yaml.md

@@ -1,11 +1,10 @@
 ---
 title : "Single Post with YAML front matter"
 date : 2017-07-20
+publishDate : "2017-07-22"
+expiryDate : "2017-07-23"
 tags : ["single", "yaml"]
 categories : ["cat1", "cat2"]
-draft : true
-publishdate : 2017-07-22
-expirydate : 2017-07-23
 menu :
   foo:
     parent : "main"

ox-hugo.el

@@ -503,9 +503,9 @@ INFO is a plist used as a communication channel."
                  (title . ,title)
                  (description . ,(org-export-data (plist-get info :hugo-description) info))
                  (date . ,date)
-                 (publishdate . ,(org-export-data (plist-get info :hugo-publishdate) info))
+                 (publishDate . ,(org-export-data (plist-get info :hugo-publishdate) info))
+                 (expiryDate . ,(org-export-data (plist-get info :hugo-expirydate) info))
                  (aliases . ,(org-export-data (plist-get info :hugo-aliases) info))
-                 (expirydate . ,(org-export-data (plist-get info :hugo-expirydate) info))
                  (isCJKLanguage . ,(org-export-data (plist-get info :hugo-iscjklanguage) info))
                  (keywords . ,(org-export-data (plist-get info :keywords) info))
                  (layout . ,(org-export-data (plist-get info :hugo-layout) info))
@@ -805,7 +805,11 @@ file."
                       (setq org-hugo--draft-state draft)
                       (setq org-hugo--tags-list tags)
                       (org-hugo-export-to-md nil :subtreep))))))
-            (user-error "It is mandatory to have a subtree with EXPORT_FILE_NAME property")))))))
+            (user-error "It is mandatory to have a subtree with EXPORT_FILE_NAME property")))
+
+        ;; Reset the state variables again at the end.
+        (setq org-hugo--draft-state nil)
+        (setq org-hugo--tags-list nil)))))
 
 ;;;###autoload
 (defun org-hugo-publish-to-md (plist filename pub-dir)