Fixed some issues with wxWidgets 2.9.1 (fixed Gerbview and Pcbnew crashes under Linux when starting. Could explain also crashes under MACOSX)
Code cleaning.
pcbnew:
    Added experimental zone fill calculations with boost::polygon
    old file zones_convert_brd_items_to_polygons.cpp has now 2 versions:
    zones_convert_brd_items_to_polygons_with_Boost.cpp use boost::polygon to calculate filled areas
    zones_convert_brd_items_to_polygons_with_BKbool.cpp use kbool (code cleaned).
    >>> to use boost polygon version:
        call cmake with option: -DUSE_BOOST_POLYGON_LIBRARY=ON
Eeschema: added patches from Yuri Khalyavin