Save grid origin in .kicad_pcb files only if not 0,0 (to keep compatibility with previous versions of pcbnew, mainly the stable version)
Very minor other fixes (set modify flag when grid origin is moved from the dialog grid)
*) add hotkey for setting the grid origin as 'S', in board editor, module editor.
*) re-position the function interface for cursor movement from BASE_SCREEN into
class EDA_DRAW_FRAME. This is a prelude to getting rid of BASE_SCREEN or
splitting it up.
jean-pierre charras
Dick Hollenbeck