Make asset icons work in subdir installs as well.

This should be the right way I guess, especially if red# is installed in a subdirectory. (untested)
removed unused function posted_date_widget

This functions seems not to be used anywhere. include/widgets.php contains widget_archive($arr) which has the same functionality.
Merge pull request #316 from dawnbreak/master

Make asset icons work in subdir installs as well.