TODOs (unsorted):
* general code review (use of per-directory-config ?)
* implement php_admin_flag and php_admin_value setting for vhosts with ldap
-* implement directory access control, similar to location
-* implement directory/location aliasing between vhosts, based on ldap
* implement logging-related directives for ldap-based vhosts
* implement require group
* implement use of other authentication methods than basic, including X509,