The patch moves the resolving logic from the renderer (where it should
not really be) to the plugin manager (controller). This is needed
because we will need the very same logic to be used at other places.

The actual loading of available updates info objects is moved back to
the plugin manager class. As we can now mockup the manager in unit
tests, this allows us to bypass the real \core\update\checker and have
unit tests for \core\plugininfo\base::available_updates().

Plugin info objects are owned by the plugin manager (composition
pattern). Even if the plugin manager is a singleton, we need to keep
explicit reference to the plugin manager that owns the plugin info so
that we can mock up things in unit tests.

Therefore this patch introduces a new property of plugin info objects
that holds the reference to the instance of the plugin manager that made
(and hence owns) the given info instance.

The only trouble here is with static methods of plugin info classes such
as \core\plugininfo\base::get_enabled_plugins(). In these cases, the
code keeps using the core_plugin_manager singleton. The solution would
be to pass the plugin manager instance as a parameter but that is not
worth of change for now, IMHO.

We can now override the plugin manager's methods in the testable
subclass while still keeping the singleton behaviour of it. The change
makes use of late static binding.

Before this patch, whenever core_plugin_manager::get_plugins() was
called, it always attached info about available updates. But this is
needed only in quite rare cases, such as when the admin is looking at
the Plugins overview and Plugins check screens. There is no need to load
this on other places and for non-admin users.

The patch removes the loading from the method
core_plugin_manager::get_plugins_of_type() and implements lazy loading
directly in the plugininfo classes so that it is loaded only when
\core\plugininfo\base::available_updates() is actually called.

The method should check against $CFG->disableupdatenotifications and not
$CFG->disableupdateautodeploy. This had to be a copy&paste mistake from
the \core\update\deployer::enabled().

While looking at it, I also fixed couple of places where this method
should and could be used.

The intention here is to make the table a little bit more compact (using
less columns) and to make use of the bootstrap based label elements if
available.

Conflicts:
	lib/upgrade.txt

Conflicts:
	version.php

Jakub Kania authored Oct 06, 2015 and John Okely committed Oct 07, 2015

With contributions from Mary Evans.