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

* 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.

* BLOCK_SELECTOR class is not longer derived from EDA_ITEM.
* Encapsulate BLOCK_SELECTOR class member variables and add access methods.
* Move HandleBlockBegin() function from block_commande.cpp to drawframe.cpp.
* Remove virtual methods from top level derived objects per future
  coding policy change.
* Remove Doxygen copydoc statement from objects derived from EDA_ITEM
  since the comments are automatically copied to the derived object.
* Removed copy and pasted Doxygen comments from objects derived from
  EDA_ITEM.

* Remove double Clone() function calls from all classes derived from
  EDA_ITEM.
* Lots of Doxygen comment warning fixes.

* All objects derived from EDA_ITEM now have consistent hit test method
  definitions.
* Remove double function calls from all classes derived from SCH_ITEM.
* Lots of Doxygen comment fixes.

Pcbnew: Added: modview. This footprint viewer frame which has the same purpose as Viewlib in Eeschema.
this viewer is built using the new  FOOTPRINT_VIEWER_FRAME class.

the GetPosition() and SetPosition() changes.  It also starts towards making m_Orientation
and m_Thickness fields private with accessors, but does not complete this latter goal.

* All header files used to create the PCB common library now compile as
  stand alone code.  This prevents the need to define them in a specific
  order to make source code compile properly.  It should also now be
  possible to relocate the source code to build the common PCB library
  to a separate folder.

* Move clarification menu icon code from base board item object to the appropriate
  object.
* Remove left over French comments.
* Coding policy fixes.

* Move menu text code from base board item object to the appropriate
  object.
* Add helper to get board layer to base board item object.

* Move schematic wire and bus break code into schematic screen object.
* Move schematic test for dangling ends into schematic screen object.
* Remove left over debugging output in schematic screen object.
* Remove unused file eeschema/cleanup.cpp.
* Fix bug in schematic line object hit test algorithm.
* Fix a string concatenation compile error added in r2752.
* Rename class WinEDA_BasicFrame to EDA_BASE_FRAME.
* Rename class WinEDA_DrawFrame to EDA_DRAW_FRAME.
* Rename class WinEDA_DrawPanel to EDA_DRAW_PANEL.

removed in drawpanel an erroneous change (was made only for a test). drc code cleaning. cmakelist.txt changes in minizip.

better compatibility with wxWidgets 2.9. Markers enhancement in pcbnew (right click can display marker info)

Code clarification about 3 confusing functions to display info: DisplayInfo (displaying a message info) and class members DisplayInfo and Display_Infos doing the same thing (see changelog)