Switch docs to MKDocs (#602)

Fixes #601. Merged in 6f87b32 from the md3 branch and did a lot of cleanup.

Changes include:

* Removed old docs build tool, templates, etc.

* Added MkDocs config file, etc.

* filename.txt => filename.md

* pythonhost.org/Markdown => Python-Markdown.github.io

* Markdown lint and other cleanup.

* Automate pages deployment in makefile with `mkdocs gh-deploy`

    Assumes a git remote is set up named "pages". Do

        git remote add pages https://github.com/Python-Markdown/Python-Markdown.github.io.git

    ... before running `make deploy` the first time.

1 files changed, 0 insertions, 88 deletions

diff --git a/docs/extensions/attr_list.txt b/docs/extensions/attr_list.txt
deleted file mode 100644
index 1951347..0000000
--- a/docs/extensions/attr_list.txt
+++ /dev/null
@@ -1,88 +0,0 @@
-title:      Attribute Lists Extension
-prev_title: Abbreviations Extension
-prev_url:   abbreviations.html
-next_title: Definition Lists Extension
-next_url:   definition_lists.html
-
-Attribute Lists
-===============
-
-Summary
--------
-
-The Attribute Lists extension adds a syntax to define attributes on the various
-HTML elements in markdown's output.
-
-This extension is included in the standard Markdown library.
-
-Syntax
-------
-
-The basic syntax was inspired by [Maruku][]'s Attribute Lists feature.
-
-[Maruku]: http://maruku.rubyforge.org/proposal.html#attribute_lists
-
-### The List ###
-
-An example attribute list might look like this:
-
-    {: #someid .someclass somekey='some value' }
-
-A word which starts with a hash (`#`) will set the id of an element.
-
-A word which starts with a dot (`.`) will be added to the list of classes 
-assigned to an element.
-
-A key/value pair (`somekey='some value'`) will assign that pair to the element.
-
-Be aware that while the dot syntax will add to a class, using key/value pairs
-will always override the previously defined attribute. Consider the following:
-
-    {: #id1 .class1 id=id2 class="class2 class3" .class4 }
-
-The above example would result in the following attributes being defined:
-
-    id="id2" class="class2 class3 class4"
-
-### Block Level ###
-
-To define attributes for a block level element, the attribute list should
-be defined on the last line of the block by itself.
-
-    This is a paragraph.
-    {: #an_id .a_class }
-
-The above results in the following output:
-
-    <p id="an_id" class="a_class">This is a paragraph.</p>
-
-The one exception is headers, as they are only ever allowed on one line.
-
-    A setext style header {: #setext}
-    =================================
-
-    ### A hash style header ### {: #hash }
-
-The above results in the following output:
-
-    <h1 id="setext">A setext style header</h1>
-    <h3 id="hash">A hash style header</h3>
-
-### Inline ###
-
-To define attributes on inline elements, the attribute list should be defined 
-immediately after the inline element with no white space.
-
-    [link](http://example.com){: class="foo bar" title="Some title!" }
-
-The above results in the following output:
-
-    <p><a href="http://example.com" class="foo bar" title="Some title!">link</a></p>
-
-Usage
------
-
-See [Extensions](index.html) for general extension usage, specify `markdown.extensions.attr_list`
-as the name of the extension.
-
-This extension does not accept any special configuration options.