Cleanup autosave_form_alter() to use the node form base ID alter hook and proper #attached properties for libraries and JavaScript settings.

Issue #1425894 by freblasty, pjcdawkins, Deciphered, eugene.ilyin, maris.abols: Added support for CKEditor.

Issue #1585408 by HEY_GERMANO, agentrickard, Deciphered: Fixed PHP Fatal error: Call to undefined function language_negotiation_get_any().

Issue #1617032 by Chaulky: After restoring a form, subsequent autosaves written to db with wrong path.

Manually save contents from TinyMCE so as to not trigger a bug with triggerSave() that messes with the cursor position.

Do not flag a form as having a saved form available if it is already the saved form that is being restored.

When restoring the form, restore it to overwrite the existing form rather than putting the new form inside the old form.

refs #1280840 by Crell: Only append our message area if it doesn't exist yet.  The odds of this behavior being called multiple times are high.

refs #1280840 by Crell: Remove unnecessary menu check.  It's already taken care of by the menu system directly.

refs #1280840 by Crell: Convert from Drupal 6-style Ajax to Drupal 7-style.  That ways way more trouble than it was worth.