Show network-activated plugins on site plugins screen

[nacin]

Per ​http://wpdevel.wordpress.com/2011/12/23/core-team-meetup-recap-multisite/, one action item is:

Include network activated plugins in the plugins menu and give message that it is automatically on for the whole network (if admin/have rights to see plugins screen).

To enable the plugins screen for a network, a super admin can go to network/settings.php and enable the menu.

Network-activated plugins should still show on this screen to site administrators. (They just can't activate them.) This should require a few tweaks to the plugins list table.

Current patch co-opts the actions list to display the text "Network Active" under the plugin name.

In IRC we've decided to punt this. I have some cleanup I am going to drop in for now.

In [20525]:

Clean up plugins.php with regards to recently edited files, deactivations, and the network admin. see #20468, #20104.

• Limit recently_activated to the site dashboard, and properly remove bulk-activated plugins from the array.
• Remove code used from before the network admin, such as the unused 'network' plugin_status.
• Don't try to deactivate a plugin already deactivated.
• Use more specific caps (manage_network_plugins) rather than is_super_admin().

Came across this issue again today, would be nice to get it in for 3.5.