Implemented the LAYER_NUM typedef (LAYER was already taken as a class name...) to represent a layer number.

Drc_On => g_Drc_On
Route_Layer_TOP => g_Route_Layer_TOP
Route_Layer_BOTTOM => g_Route_Layer_BOTTOM
Track_45_Only_Allowed => g_Track_45_Only_Allowed

* Complete encapsulation of the MODULE class.
* Complete encapsulation of the EDA_TEXT class.
* Encapsulate most of the ZONE_CONTAINER class.
* Add pcbcommon library as a dependency for reSWIGging the scripting
  support.  This should cover most dependency cases.

* Encapsulate most of the MODULE class.
* Start encapsulating the DIMENSION class.
* Lay some groundwork for EDA_TEXT encapsulation.
* Move cleverly hidden MODULE functions into class_module.cpp.
* Use std::swap to exchange TEXTE_PCB values for undo/redo.
* Remove unused members from MODULE class.
* The usual coding policy and documentation fixes.

Pcbnew: fix Bug #1148785 (pcbnew crashes when using only one layer in autorouter ) , and a minor bug in dialog cleanup.

* Improve MSG_PANEL_ITEM to handle message panel information.
* Create containers for passing message panel items between objects and
  the message panel.
* Rename EDA_ITEM::DisplayInfo to EDA_ITEM::GetMsgPanelInfo.
* Remove all direct manipulation of EDA_DRAW_FRAME from all objects derived
  from EDA_ITEM.

All: remove macros  MAX, MIN, ABS from macros.h and replace these macros by std::max, std::min and std::abs (mainly found in old code).

Code cleaning in autoroute functions.

autoroute functions: code cleaning

Some code cleaning in autoroute functions.

Minor code cleaning in autoroute files.

fix nanometer compatibility.
minor code and comments cleaning (although theses files need a lot of code cleaning)