Add support for pandoc-style YAML front matter fences ---/... (fixes #153).

README.md

@@ -342,7 +342,7 @@ ignores common forms of "front matter". To match differently, specify a custom
 The default value:
 
 ```js
-/^(---|\+\+\+)$[^]*?^\1$(\r\n|\r|\n)/m
+/((^---$[^]*?^---$)|(^\+\+\+$[^]*?^(\+\+\+|\.\.\.)$))(\r\n|\r|\n|$)/m
 ```
 
 Ignores [YAML](https://en.wikipedia.org/wiki/YAML) and

lib/shared.js

@@ -7,7 +7,8 @@
 module.exports.newLineRe = /\r[\n\u0085]?|[\n\u2424\u2028\u0085]/;
 
 // Regular expression for matching common front matter (YAML and TOML)
-module.exports.frontMatterRe = /^(---|\+\+\+)$[^]*?^\1$(\r\n|\r|\n|$)/m;
+module.exports.frontMatterRe =
+  /((^---$[^]*?^---$)|(^\+\+\+$[^]*?^(\+\+\+|\.\.\.)$))(\r\n|\r|\n|$)/m;
 
 // Regular expression for matching inline disable/enable comments
 const inlineCommentRe =

test/front-matter-title-pandoc.json

@@ -0,0 +1,4 @@
+{
+  "default": true,
+  "MD041": true
+}

test/front-matter-title-pandoc.md

@@ -0,0 +1,6 @@
++++
+title: "Welcome to pandoc!"
+date:  2015-11-17 16:16:01 -0600
+...
+
+Some plain text here.