Refactoring and flexibility changes

* Split game module into game and game_interface
* Move core_lib to corelib
* Move miniwindow to corelib
* Introduce init.lua script for initializing the client, giving much more flexibility
* OTClient is no longer Application derived and is much simpler

modules/corelib/widgets/uicheckbox.lua

@@ -0,0 +1,12 @@
+UICheckBox = extends(UIWidget)
+
+function UICheckBox.create()
+  local checkbox = UICheckBox.internalCreate()
+  checkbox:setFocusable(false)
+  checkbox:setTextAlign(AlignLeft)
+  return checkbox
+end
+
+function UICheckBox:onClick()
+  self:setChecked(not self:isChecked())
+end