rework on graphics.cpp, implement some GFX with lua

modules/gfx/gfx.otmod

@@ -0,0 +1,15 @@
+Module
+  name: gfx
+  description: Contains utilities for generating graphics effects
+  author: OTClient team
+  website: https://github.com/edubart/otclient
+  version: 0.2
+  autoLoad: true
+  dependencies:
+    - core
+
+  onLoad: |
+    require 'gfx'
+    return true
+
+