[WIP] Refactor to remove regular expressions

...in favour of an algorithmic approach.

*   [x] `yamlFrontMatter`
*   [x] `newline`
*   [x] `code`
*   [x] `horizontalRule`
*   [x] `escape`
*   [x] `deletion`
*   [x] `break`
*   [x] `inlineText`
*   [x] `fences`
*   [x] `heading`
*   [x] `lineHeading`
*   [ ] `blockquote`
*   [ ] `list`
*   [x] `html`
*   [x] `definition`
*   [x] `footnoteDefinition`
*   [ ] `looseTable`
*   [ ] `table`
*   [ ] `paragraph`
*   [x] `autoLink`
*   [x] `url`
*   [x] `tag`
*   [ ] `link`
*   [x] `reference`
*   [x] `shortcutReference`
*   [ ] `strong`
*   [x] `emphasis`
*   [x] `inlineCode`

Regressions (either todo or in the subsequent major release):

*   The strictness required by CommonMark for HTML comments is loosened;
*   Malformed HTML block elements are not supported.

[ci skip]

.jscs.json

@@ -138,7 +138,7 @@
     "else"
   ],
   "requireLineFeedAtFileEnd": true,
-  "maximumLineLength": 78,
+  "maximumLineLength": 79,
   "requireCapitalizedConstructors": true,
   "safeContextKeyword": "self",
   "requireDotNotation": true,