Clean deprecated code (property "special" removed from mod descriptor)

htdocs/core/modules/modModuleBuilder.class.php

@@ -51,8 +51,6 @@ class modModuleBuilder extends DolibarrModules
         $this->version = 'experimental';
         // Key used in llx_const table to save module status enabled/disabled (where MYMODULE is value of property name of module in uppercase)
         $this->const_name = 'MAIN_MODULE_'.strtoupper($this->name);
-        // Where to store the module in setup page (0=common,1=interface,2=others,3=very specific)
-        $this->special = 1;
         // Name of image file used for this module.
         $this->picto='technic';