* Rename all ADD_MENUITEM_* functions to AddMenuItem and move them to
  wxstruct.h since they are used by the Kicad main frame classes.
* Move SET_BITMAP and SETBITMAPS definitions to wxstruct.h.
* Fix a bug in SET_BITMAPS that prevented enabling menu item images on
  OSX.
* Rename MsgItem to EDA_MSG_ITEM.
* Remove redundant includes from modified files.
* Doxygen and coding style policy fixes.