* Fix bug in PCBNEW dialog_pad_properties.cpp that I introduced several days ago.
  The m_Master_Pad stuff is stored in the PCB_EDIT_FRAME's BOARD_DESIGN_SETTINGS,
  not in the FOOTPRINT_EDIT_FRAME's BOARD_DESIGN_SETTINGS (i.e. not stored in 
  the module editor's dummy BOARD).  Now we properly initialize the
  DIALOG_PAD_PROPERTIES::m_Pad_Master reference to the correct master pad
  dope, instead of to the dummy module BOARD's master pad, which is not used.