New conversion routines and sin/cos implementation for angles in decidegrees

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

Eeschema: always stores sheet filename in unix-like notation, and fix a  bug when editing sheet file  name.
Pcbnew: add PDF format  for drill map generation.
Plotter classes: tweaking code.

Pcbnew: drill files creation: better dialog to create driil files, map files and report file. Code cleaning

Mainly to plot drill maps, but can be used to plot boards, for documentation.
The print svg still exists, but the plot SVG has more options (mirroring, holes in pads),
however  print svg allows color print, and full board printing, and plot does not.

Kicad manager: shows now svg files in tree files.
Pcbnew: fix incorrect printing (board out of page) when creating drill map in postscript format ( noticeable mainly for small boards)

3D viewer: fix incorrect scaling factor when using nanometers.
Very minor other fixes

Add patch from Lorenzo Marcantonio. Fix some warning issues, and zlib issue under Windows (zlib sources added)

  * Removed Pcb_Frame argument from BOARD() constructor, since it precludes
    having a BOARD being edited by more than one editor, it was a bad design.
    And this meant removing m_PcbFrame from BOARD.
  * removed BOARD::SetWindowFrame(), and BOARD::m_PcbFrame
  * Removed the global BOARD_DESIGN_SETTINGS which was in class_board.cpp
  * added BOARD_DESIGN_SETTINGS to the BOARD class, a full instance
  * a couple dialogs now only change BOARD_DESIGN_SETTINGS when OK is pressed,
    such as dialog_mask_clearance, dialog_drc, etc.
  * Removed common/pcbcommon.cpp's int g_CurrentVersionPCB = 1 and replaced it
    with build_version.h's #define BOARD_FILE_VERSION, although there may be a
    better place for this constant.
  * Made the public functions in PARAM_CFG_ARRAY be type const.
    void SaveParam(..) const and void ReadParam(..) const
  * PARAM_CFG_BASE now has virtual destructor since we have various way of
    destroying the derived class and boost::ptr_vector must be told about this.
  * Pass const PARAM_CFG_ARRAY& instead of PARAM_CFG_ARRAY so that we can use
    an automatic PARAM_CFG_ARRAY which is on the stack.\
  * PCB_EDIT_FRAME::GetProjectFileParameters() may no longer cache the array,
    since it has to access the current BOARD and the BOARD can change.
    Remember BOARD_DESIGN_SETTINGS are now in the BOARD.
  * Made the m_BoundingBox member private, this was a brutally hard task,
    and indicative of the lack of commitment to accessors and object oriented
    design on the part of KiCad developers.  We must do better.
    Added BOARD::GetBoundingBox, SetBoundingBox(), ComputeBoundingBox().
  * Added PCB_BASE_FRAME::GetBoardBoundingBox() which calls BOARD::ComputeBoundingBox()

* Use version of DateAndTime that returns a wxString and delete the
  version that takes a char* as it is no longer required.
* Merge StrNumICmp() and StrLenNumICmp() into StrLenNumCmp() to create a
  single function for comparing strings with integers and remove a lot
  of duplicate code.
* Remove unused strupper from string.cpp.
* Use wxArrayString for sorting the EDA_LIST_DIALOG contents.

* 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.

* Changed <wx-2.8/xml/xml.h> to "xnode.h" in pcbnew_config.cpp to fix bug
  when building against wxWidgets 2.9 and above.
* Convert broken wxXmlNode code to use XNODE.
* Overloaded XNODE constructor for creating child nodes.
* Translate French naming conventions.
* Translate French comments.
* Remove tabs from several source files.
* Coding style policy and Doxygen comment fixes.

Minor fixes and enhancements.

Use UTF-8 encoding only in kicad files. Under Linux, this was already the case. Under Windows, texts with  non ascii characters must be corrected.
This ensure compatibility between platforms.

Change board bounding box calculation to include all board items by default in pcbnew. Add a parameter to look for board edges only.

Pcbnew: Fixed minor problems (bugs 568357 and 568356). Changed French word COTATION to DIMENSION in class COTATION (now class DIMENSION)

removed global variables and a lot of redundancies

* Fix debug asserts when passing NULL pointers to wxAuiPaneInfo.
* Fix Kicad main window sash sizer bug when using wxAui.
* Remove specctra_test from Visual Studio builds to prevent build errors.
* Add WIN32 to layer widget test so it will build properly on Visual Studio.
* Fixed compiler conversion warnings in PCBNew.
* Fixed worksheet print scaling in PCBNew.
* Minor code renaming.

  * Moved ReturnLayerName() to static BOARD::GetDefaultLayerName() and migrated
    to a Specctra DSN compatible default layer naming scheme:
        Component becomes Front, Copper becomes Back.
  * set_color.h: Cmp becomes Front, Cu becomes Back.
  * D_PAD::DisplayInfo() changed to use actual copper layer names.
  * more layer setup dialog work, moved all programmatic wxControl instantiation
    into the wxFormbuilder environment, but this is fraught with danger:
    wxFlexGridSizer used the tallest control to establish the row heights, so
    be careful about changing control borders in the scroll panel. The vertical
    size can explode since just a couple of pixels times the number of rows
    is substantial.  Currently I am setting a 5 pixel border only left, top, and right
    but not bottom.
  * Set copper layer count is back in place as a hack until I can get the enabled
    layer bit map fully operational.

* Translate source files D through L in pcbnew.
* Add translate tag for comments that did not translate correctly.