New Windowlist plugin

[Nick Schermer]

[Clicked the send button too early... sorry...]

I've rewritten the windowlist plugin and I'd like to have
some feedback about the changes I've made.

Changelog:
 - Choose between an icon or arrow button.
 - Blink button when an application needs attention
  - Multiscreen compatible (can someone please test this??
   there was a bug about this on bugzilla...)
 - Extra option to disable workspace actions
 - Left click menu item: Show window in native workspace
   Right click: Show window in current workspace

 - Removed: Right click shows action menu.

Now I (and Jasper) like to know what you guys think about
those new options and if it's ok to remove the action menu.
I can easily revert it or add an another option (but rather not) to
select what each mouse button should do.

Feel free to test and comment on this plugin and if you
don't like the current click behaviour: post your preferred actions.

Greets,
Nick

Apply patch with: patch -Np0 -s -i xfce4-panel-windowlist.patch