Clean support of public calendars, add support of private calendars

config

@@ -36,6 +36,10 @@ stock = utf-8
 # Access method
 # Value: None | htpasswd | LDAP
 type = None
+# Usernames used for public calendars, separated by a comma
+public_users = public
+# Usernames used for private calendars, separated by a comma
+private_users = private
 # Htpasswd filename
 htpasswd_filename = /etc/radicale/users
 # Htpasswd encryption method