Extend get_links_list() to allow for different header tags around category names

[anselm1109]

the get_links_list() function currently encloses the category names in <h2> tags. Let's extend it so that the user can specify which tag to enclose it in.

This works by simply adding two more parameters to the function and a small change to the code on line 551. The function still defaults to current setting so that nothing is changed for past versions.

[rob1n]

get_links_list() is deprecated in favor of wp_list_bookmarks(), which has support for other headers than <h2>.