phpdoc cleanup:

 * add @category (Piwik => 'core', Piwik_Plugins => 'plugins')
 * in core, use @package and @subpackage more consistently to group files/classes; exception is DataFiles/*, PluginsFunctions/*, and SmartyPlugins/*
 * in plugins, @package is the plugin name
 * removed '@param none' -- not a phpdoc convention
 * '@throws' and '@return void' are also not phpdoc conventions, but are widely used elsewhere, e.g., Smarty & Zend


git-svn-id: http://dev.piwik.org/svn/trunk@1420 59fd770c-687e-43c8-a1e3-f5a4ff64c105