Making better use of class autoloading too.

- Fix titles on error pages

* renamed FeedSub plugin to OStatus
* now setting avatar on subscriptions
* general fixes for subscription
* integrated PuSH hub to handle only user timelines on canonical ID url; sends updates directly
* set $config['feedsub']['nohub'] = true to test w/ foreign feeds that don't have hubs (won't actually receive updates though)
* a few bits of code documentation
* HMAC support for verified distributions (safest if sub setup is on HTTPS)

And a couple core changes:
* minimizing HTML output for exceptions in API requests to aid in debugging
* fix for rel=self link in apitimelineuser when id given

This does not not yet include any of the individual subscription management (Salmon notifications for sub/unsub, etc) nor a nice UI for user subscriptions.
Needs some further cleanup to treat posts as status updates instead of link references.

This reverts commit 5ab709b7.

Missed this one yesterday...

* doesn't
* won't
* isn't
* don't

Error page fix: use class static accessor correctly, suppress notices if we don't have the error code listed

Add an array of arguments to isReadOnly() method of actions, to let
them change their results depending on what actions are called.
Primarily used by the 'api' action. Ideally in the future that will be
multiple actions. But this might still be useful.

Add an array of arguments to isReadOnly() method of actions, to let
them change their results depending on what actions are called.
Primarily used by the 'api' action. Ideally in the future that will be
multiple actions. But this might still be useful.