* Allow to select units in components that have more than one right in the
  component chooser dialog.
* Keep chosen unit in history.
* Show preview of current component unit as thumbnail image next to the
  description box.
* Fixes lp:1280567

* Apply Henner Zeller's patch to add connecting line from reference and labels to component position whilst moving to help identify which component the reference or label belongs too

Add a workaround to fix a new bug in wxWidgets 3.0 ( Windows specific ) which shows icons only with a size = 16x16 in menus which have attribute wxITEM_CHECK

Fix some incorrect icons (which were using a not supported font for texts). Add ps_router icon from Konstantin Baranovskiy.

Moved netnames (GAL specific layers) to a separate enum, to avoid saving/reading their settings from files.
Added a check for the number of PCB_VISIBLE elements.
Worksheet & general purpose overlay layers are visible by default.

Changed BOARD_DESIGN_SETTINGS::m_VisibleElements from int to long, to assure at least 32 bits length (without depending on the platfrom int size).

Add missing calls to Show( false ) to some main frames (Kicad, eeschema, gerbview), to force config saving when closing these windows.
Code cleanup and minor coding style fixes  in footprint_wizard_frame

Add EDA_BASE_FRAME::Show() and call SaveSettings() only from there for all derived wxFrames.  Remove calls to SaveSettings() elsewhere.

Remove g_LibraryNames and all supporting infrastructure from pcbnew.  FP_LIB_TABLE is now local to major wxFrames.

Pcbnew: fix bug #1272714 . Code cleanup: use 2 different enums for pad shapes and pad drill shapes. Remove never used pad shape.

move ${Boost_LIBRARIES} into cvpcb, pcbnew, _pcbnew and out of github, because worker threads used regardless of github

   To use multiple working threads.  This entailed adding KiCad typedefs:
*) Add typedefs for MUTEX and MUTLOCK which mask the actual choices for the project.
*) Add FOOTPRINT_LIST::DisplayErrors( wxWindow* ) which is a single strategy for
   showing aggregated load errors.  Although what's there is only scaffolding
   and needs a volunteer who knows HTML pretty well.
*) Ensure all callers of ReadFootprintFiles() use the new DisplayErrors() function.   
*) Push utf8.cpp and utf8.h into common library for open use.

* Make the tool bar dockable.
* Enable the overflow control in the tool bar in case the it does not fit in
  it's parent window.
* Fix some wxAuiPaneInfo usage issues.
* Remove unused wxAuiPaneInfo objects.
* Move perspective saving and loading into EDA_BASE_FRAME object in preparation
  for extending this to all frame windows.