Using ajax and the Request Handler for Post Drafts

Now printing the md_cheatsheet.html
    I made a function to get the contents of the html file md_cheatsheet.html.
    I was going to have it print when the post page was requested, but I
    removed that function and just printed get_file_contents of that file
    (under that same condition).

Removed the testing navigation from post.php page

Moved the instanstiation site of the markdown parser
    The markdown parser is now being included and instanstiated in the request
    handling logic where it is being used.

No longer echoing the post.php form
    Now it's just an regular html form (modified from the echoed one now of
    course).

Now handling the draft previews with ajax
    Removed the php that was handling the previewing and now using an embedded
    javascript the utilizes xmlrequests.

Added inputs to the draft form
    Added an area for title, subtitle, and tags. Also added buttons for
    previewing, saving, and publishing drafts.

Added conditions to the request handler in functions.php
    Now if data=prev parsedown in included and a Parsedown object is
    instanstiated and used to parse the ajax form to generate a preview

    This condition will be modified later to create a Parsedown object for
    saving and publishing drafts as well

Added and ignored a changelog