reorganize modules

modules/core/core.otmod

@@ -3,19 +3,15 @@ Module
   description: Contains lua classes, functions and constants used by other modules
   author: OTClient team
   website: https://github.com/edubart/otclient
+
+  // core must be loaded before other modules
   autoLoad: true
+  autoLoadPriority: 10
+
+  // NOTE: order does matter
   dependencies:
     - core_fonts
     - core_styles
-
-  onLoad: |
-    require 'ext/table'
-    require 'ext/string'
-    require 'constants'
-    require 'util'
-    require 'dispatcher'
-    require 'widget'
-    require 'ui'
-    require 'gfx'
-    return true
+    - core_scripts
+    - core_widgets