Disable special string insertion by Org; Title sanitization

- Blackfriday automatically renders "--" as en-dash, "---" as em-dash and
  so on. So there is no need for Org to replace those with the HTML
  special characters in the Markdown itself.  This also makes the
  Markdown more readable.
- Titles are now sanitized. HTML anyways does not allow bold, italics,
  etc markup in the <title> section. Now Markdown markup for the same
  are removed from the title variable in front matter.

example-site/content-org/all-posts.org

@@ -443,6 +443,26 @@ The strings in these two columns should look the exact same.
 *Note:* There is a rendering issue is Row 5 above. That seems to be a
  corner case, because notice that Row 6 looks fine just because there
  was a trailing period. /Will live with this issue for now./
+** /ndash/ `and` *mdash*
+:PROPERTIES:
+:EXPORT_FILE_NAME: ndash-and-mdash
+:EXPORT_DATE: 2017-07-22
+:END:
+The strings in these two columns should look the exact same.
+|   | Character | Rendered Actual | Rendered Expection |
+|---+-----------+-----------------+--------------------|
+| 1 | Hyphen    | a - b           | a - b              |
+| 2 | Ndash     | a -- b           | a – b              |
+| 3 | Mdash     | a --- b           | a — b              |
+| 4 | Ellipsis  | a ... b           | a … b              |
+#+TBLFM: $1=@#-1
+*** Title sanitization
+This post has italics, monospace and bold in the title. This is to
+test that those markup characters *do not* end up in the =title= front
+matter of the post because HTML does not allow markup in the =<title>=
+section.
+
+So the title of this post should read as "ndash and mdash".
 * Footnotes Test                                                   :footnote:
 ** Footnotes 1
 :PROPERTIES:

example-site/content/posts/dealing-with-underscores.md

@@ -14,4 +14,4 @@ This underscore also shouldn't be escaped as it's in an emoji
 code: :raised_hands:
 
 And these ones should be eventually removed and <span class="underline">underline</span> the text
-(_Requires CSS to do so._) &#x2013; **Org syntax**.
+(_Requires CSS to do so._) -- **Org syntax**.

example-site/content/posts/ndash-and-mdash.md

@@ -0,0 +1,25 @@
++++
+title = "ndash and mdash"
+date = 2017-07-22
+tags = ["body"]
+draft = false
++++
+
+The strings in these two columns should look the exact same.
+
+   | Character | Rendered Actual | Rendered Expection
+---|-----------|-----------------|-------------------
+ 1 | Hyphen    | a - b           | a - b
+ 2 | Ndash     | a -- b          | a – b
+ 3 | Mdash     | a --- b         | a — b
+ 4 | Ellipsis  | a ... b         | a … b
+
+
+## Title sanitization {#title-sanitization}
+
+This post has italics, monospace and bold in the title. This is to
+test that those markup characters **do not** end up in the `title` front
+matter of the post because HTML does not allow markup in the `<title>`
+section.
+
+So the title of this post should read as "ndash and mdash".

example-site/content/posts/shortcode-src-blocks.md

@@ -1,5 +1,5 @@
 +++
-title = "Source blocks with Hugo `highlight` shortcode"
+title = "Source blocks with Hugo highlight shortcode"
 date = 2017-07-13T17:57:58-04:00
 tags = []
 draft = false

ox-hugo.el

@@ -133,6 +133,7 @@ directory where all Hugo posts should go by default."
                    (:with-toc nil "toc" nil) ;No TOC by default
                    (:preserve-breaks nil "\\n" t) ;Preserve breaks so that text filling in Markdown matches that of Org
                    (:with-smart-quotes nil "'" nil) ;Don't use smart quotes; that is done automatically by Blackfriday
+                   (:with-special-strings nil "-" nil) ;Don't use special strings for ndash, mdash; that is done automatically by Blackfriday
                    (:hugo-front-matter-format "HUGO_FRONT_MATTER_FORMAT" nil     org-hugo-front-matter-format)
                    (:hugo-level-offset "HUGO_LEVEL_OFFSET" nil 1)
                    (:hugo-section "HUGO_SECTION" nil org-hugo-default-section-directory)
@@ -639,6 +640,10 @@ INFO is a plist used as a communication channel."
                     (org-export-data (plist-get info :hugo-tags) info) " "
                     (org-export-data (plist-get info :tags) info))))
          (title (org-export-data (plist-get info :title) info))
+         ;; Sanitize title.. cannot do bold, italics, monospace in title
+         (title (replace-regexp-in-string "\\\\?`" "" title))
+         (title (replace-regexp-in-string "\\`__?\\|\\`\\*\\*?\\|__?\\'\\|\\*\\*?\\'" "" title))
+         (title (replace-regexp-in-string " __?\\|__? \\| \\*\\*?\\|\\*\\*? " " " title))
          (menu-alist (org-hugo--parse-menu-prop-to-alist (plist-get info :hugo-menu)))
          (menu-alist-override (org-hugo--parse-menu-prop-to-alist (plist-get info :hugo-menu-override)))
          ;; If menu-alist-override is non-nil, update menu-alist with values from that.