Plugins Dashboard Widget: Dont show installed plugins (or offer to install them)

[DD32]

As Chris Moody suggested: ​http://comox.textdrive.com/pipermail/wp-testers/2009-January/011011.html

Personally i think skipping the plugin if its already installed would be best, Not sure how much overhead it'd introduce matching the plugins up (Slug/Name in Widget vs. the actual plugins WP has installed vs. reading plugins from directory to get names, etc.)

Could possibly be a good candidate to introduce a cached option inside WP for a WP-Slug => Local Plugin file/Plugin Name lookup, Which would aid in displaying which plugins couldnt be automatically checked for updates too..

[Viper007Bond]

Needs testing and the while() could be troublesome if it somehow gets stuck in an infinite loop, but I tested it on my localhost and it seems to work great. Akismet no longer shows up under "Most Popular" for example.

[Viper007Bond]

Cache slugs, avoid using get_plugins() on every page load

[Viper007Bond]

Make sure we never infinite loop and don't autoload the option

[Viper007Bond]

Code improvements care of rmccue and DD32

[Viper007Bond]

More code streamlining care of rmccue

[Viper007Bond]

More redundancy removal thanks to rmccue (why don't I think of these things when writing it?)

[Viper007Bond]

Don't consolidate too much, we still need $plugin_slugs

[ryan]

Needs update now that SimplePie has landed.

[Viper007Bond]

Refresh for 2.8 / SimplePie

[Viper007Bond]

Use the new transient API instead of an option to cache the plugin slugs

[Viper007Bond]

Should be good to go now. Installed a couple of the current "Most Popular" plugins and they stopped showing up in the list.

The transient API is really slick BTW. Gotta remember to make more use of that in the future. I set the caching time to 24 hours though, dunno if that's an acceptable cache time for caching the list of installed plugin slugs (it's updated on a visit to the plugins page anyway).

[ryan]

(In [10738]) Don't show already installed plugins in the Plugins dashboard widget. Props Viper007Bond. fixes #8781