mod_admin: Resources in the meta category can have 'features'

Features are certain resource properties (usually in the form of
checkboxes) that decide what to show or hide on certain pages in the
admin. Used for example to control where to show address and geodata
edit boxes.
(cherry picked from commit 184397df3f38ce103674d133a1d606f7ce98fef3)

Conflicts:
	NEWS
	modules/mod_admin/templates/admin_edit.tpl