pass parameters to get_categories filters

[ryanscheuermann]

In the get_categories function, the following filters could be passed the parameters array:

• list_cats_exclusions
• get_categories

For instance:

$exclusions = apply_filters('list_cats_exclusions', $exclusions, $r );

This would greatly enhanced a plugin's ability to manage categories and even allow additional plugin-based parameters to be passed to get_categories, wp_list_categories, etc.

pass params to filters in get_categories

(In [4013]) Pass arg array to get_categories filters. Props ryanscheuermann. fixes #2934