More clearly separate baseurlpath from the filesystem paths.

Frequently people put fs paths in baseurlpath or URL paths in
the other settings. By more clearly separating these two classes
of options I hope to reduce confusion a bit.

config-templates/config.php

@@ -11,11 +11,15 @@ $config = array(
      *******************************/
 
     /*
-     * Setup the following parameters to match the directory of your installation.
+     * Setup the following parameters to match your installation.
      * See the user manual for more details.
-     *
-     * Valid format for 'baseurlpath' is:
+     */
+
+    /*
+     * baseurlpath is a *URL path* (not a filesystem path).
+     * A valid format for 'baseurlpath' is:
      * [(http|https)://(hostname|fqdn)[:port]]/[path/to/simplesaml/]
+     * (note that it must end with a '/')
      *
      * The full url format is useful if your SimpleSAMLphp setup is hosted behind
      * a reverse proxy. In that case you can specify the external url here.
@@ -25,15 +29,21 @@ $config = array(
      * reverse proxy).
      */
     'baseurlpath' => 'simplesaml/',
-    'certdir' => 'cert/',
-    'loggingdir' => 'log/',
-    'datadir' => 'data/',
 
     /*
-     * A directory where SimpleSAMLphp can save temporary files.
-     *
-     * SimpleSAMLphp will attempt to create this directory if it doesn't exist.
+     * The following settings are *filesystem paths* which define where
+     * SimpleSAMLphp can find or write the following things:
+     * - 'certdir': The base directory for certificate and key material.
+     * - 'loggingdir': Where to write logs.
+     * - 'datadir': Storage of general data.
+     * - 'temdir': Saving temporary files. SimpleSAMLphp will attempt to create
+     *   this directory if it doesn't exist.
+     * When specified as a relative path, this is relative to the SimpleSAMLphp
+     * root directory. 
      */
+    'certdir' => 'cert/',
+    'loggingdir' => 'log/',
+    'datadir' => 'data/',
     'tempdir' => '/tmp/simplesaml',
 
     /*