Make save/restore default feature, the configure option for save/restore removed from configure script and save/restore made available forever. All code now assume it is exists. Bochs save/restore tree previosly called "save_restore" renamed to "bochs" tree and it will be havily used everywhere, starting from save/restore and ending by various bochs debugger functions. I am going to rework debugger code to get rid of debug CPU access functions and use this "bochs" param tree instead
- new symbol BX_USE_PCIVGA_SMF for the experimental PCI VGA device
- pcivga.cc: removed unnecessary include statement
- pcivga.cc: fixed two warnings
- pcivga.h: removed unnecessary symbol BX_IODEV_PCIVGA_H