Pcbnew: fix Pcbnew name capitalization in messages.
About dialog: add a link to kicad-pcb.org

  * Save all visibilities, layer and render, in BOARD and restore on load.

Minor other enhancements and code cleaning.

Pcbnew: prepare work on new algos for connections calculations.

Remove obsolete foldr resources/icons.
Updates svg icons in folder resources.

Add a new schematic item: SCH_BITMAP. One can insert now images in a schematic.
Add Fabrizio Tappero as contributor  in Kicad About dialog

dialog_about: add translator name.

commit patch from Kenta Yonekura (adding Japanese language) and add  Kenta Yonekura to translator list in about dialog

Pcbnew: For zone filling algo, change the default polygon library from Kbool to Boost::polygon (USE_BOOST_POLYGON_LIBRARY default is ON). (need to rebuild makefile)
Gerbview: added decimal format for coordinates, sometimes found in Gerber files.

Design rule dialog: use wxLC_VIRTUAL options in wxListBoxes tu speed  up nets lists display (which was very long for board with a lot of nets)