Updated modules to allow for partial overrides without errors

Only define functions if they have not been defined before, e.g. in themes. This makes it possible to override parts of a module and still use the other functions.

mod/cb.php

@@ -4,21 +4,28 @@
  * General purpose landing page for plugins/addons
  */
 
-
+if(! function_exists('cb_init')) {
 function cb_init(&$a) {
 	call_hooks('cb_init');
 }
+}
 
+if(! function_exists('cb_post')) {
 function cb_post(&$a) {
 	call_hooks('cb_post', $_POST);
 }
+}
 
+if(! function_exists('cb_afterpost')) {
 function cb_afterpost(&$a) {
 	call_hooks('cb_afterpost');
 }
+}
 
+if(! function_exists('cb_content')) {
 function cb_content(&$a) {
 	$o = '';
 	call_hooks('cb_content', $o);
 	return $o;
-}
+}
+}