Add date parsing from property drawer

Also fix the case of "isCJKLanguage" front matter variable.. though, I
believe, hugo does not care about the case there.

Add a test file prop-drawer-parsing.org

ox-hugo.el

@@ -250,7 +250,11 @@ INFO is a plist used as a communication channel."
 INFO is a plist used as a communication channel."
   (let* ((fm-format (org-export-data (plist-get info :hugo-front-matter-format) info))
          (hugo-date-fmt "%Y-%m-%dT%T%z")
-         (date (or (org-string-nw-p (org-export-get-date info hugo-date-fmt))
+         (date (or ;; Get the date from the subtree property `EXPORT_DATE' if available
+                   (org-export-data (plist-get info :date) info)
+                   ;; Else try to get it from the #+DATE keyword in the Org file
+                   (org-string-nw-p (org-export-get-date info hugo-date-fmt))
+                   ;; Else finally set the date to the current date
                    (format-time-string hugo-date-fmt (current-time))))
          (data `((title . ,(org-export-data (plist-get info :title) info))
                  (date . ,date)
@@ -262,7 +266,7 @@ INFO is a plist used as a communication channel."
                  (publishdate . ,(org-export-data (plist-get info :hugo-publishdate) info))
                  (expirydate . ,(org-export-data (plist-get info :hugo-expirydate) info))
                  (type . ,(org-export-data (plist-get info :hugo-type) info))
-                 (iscjklanguage . ,(org-export-data (plist-get info :hugo-iscjklanguage) info))
+                 (isCJKLanguage . ,(org-export-data (plist-get info :hugo-iscjklanguage) info))
                  (weight . ,(org-export-data (plist-get info :hugo-weight) info))
                  (markup . ,(org-export-data (plist-get info :hugo-markup) info))
                  (slug . ,(org-export-data (plist-get info :hugo-slug) info))

tests/org/prop-drawer-parsing/prop-drawer-parsing.org

@@ -0,0 +1,17 @@
+#+TITLE: My Blog
+#+HUGO_EXPORT_DIR: ../../md/
+#+HUGO_SECTION: posts
+
+# 1. Load `ox-hugo'
+# 2. M-x org-hugo-walk-headlines
+
+* Test setting the =draft= variable in front matter
+:PROPERTIES:
+:EXPORT_HUGO_DRAFT: true
+:END:
+Something. /Run =C-c C-e H O= with point in this subtree./
+* Test setting the =date= variable in front matter
+:PROPERTIES:
+:EXPORT_DATE: Feb 2, 2002
+:END:
+Something Else. /Run =C-c C-e H O= with point in this subtree./