replace NULL with null

Another global search-and-replace update. Here, I've replaced the PHP
keyword 'NULL' with its lowercase version. This is another PEAR code
standards change.

darcs-hash:20081223192129-84dde-4a0182e0ec16a01ad88745ad3e08f7cb501aee0b.gz

lib/common.php

@@ -58,16 +58,16 @@ $config =
               'server' => 'localhost',
               'theme' => 'default',
               'path' => '/',
-              'logfile' => NULL,
+              'logfile' => null,
               'fancy' => false,
               'locale_path' => INSTALLDIR.'/locale',
               'language' => 'en_US',
               'languages' => get_all_languages(),
               'email' =>
-              array_key_exists('SERVER_ADMIN', $_SERVER) ? $_SERVER['SERVER_ADMIN'] : NULL,
-              'broughtby' => NULL,
+              array_key_exists('SERVER_ADMIN', $_SERVER) ? $_SERVER['SERVER_ADMIN'] : null,
+              'broughtby' => null,
               'timezone' => 'UTC',
-              'broughtbyurl' => NULL,
+              'broughtbyurl' => null,
               'closed' => false,
               'inviteonly' => false,
               'private' => false),
@@ -82,19 +82,19 @@ $config =
               'image' => 'http://i.creativecommons.org/l/by/3.0/88x31.png'),
         'mail' =>
         array('backend' => 'mail',
-              'params' => NULL),
+              'params' => null),
         'nickname' =>
         array('blacklist' => array(),
               'featured' => array()),
         'profile' =>
         array('banned' => array()),
         'avatar' =>
-        array('server' => NULL),
+        array('server' => null),
         'public' =>
         array('localonly' => true,
               'blacklist' => array()),
         'theme' =>
-        array('server' => NULL),
+        array('server' => null),
         'throttle' =>
         array('enabled' => false, // whether to throttle edits; false by default
               'count' => 20, // number of allowed messages in timespan
@@ -107,7 +107,7 @@ $config =
               'encryption' => true,
               'resource' => 'uniquename',
               'password' => 'blahblahblah',
-              'host' => NULL, # only set if != server
+              'host' => null, # only set if != server
               'debug' => false, # print extra debug info
               'public' => array()), # JIDs of users who want to receive the public stream
         'sphinx' =>
@@ -140,7 +140,7 @@ $config['db'] =
         'class_location' => INSTALLDIR . '/classes',
         'require_prefix' => 'classes/',
         'class_prefix' => '',
-        'mirror' => NULL,
+        'mirror' => null,
         'db_driver' => 'DB', # XXX: JanRain libs only work with DB
         'quote_identifiers' => false,
         'type' => 'mysql' );