vbox: add support for 4.3 APIs
    
    Makefile.am, vbox_V4_3.c and vbox_driver.c do regular
    modifitions to support a new version of APIs.
    
    vbox_tmpl.c basically fixes incompatibilities since 4.2.
    
    The affected incompatibilities of 4.3 are:
    * IMachine::Delete() has been renamed to IMachine::deleteConfig()
    * IMedium::CreateBaseStorage() now accepts multiple variant values
    * IDisplay::GetScreenResolution() now returns the display position
      in the guest
    * IMachine now has multiple IUSBControllers and IUSBDeviceFilters
      handles USB device filters instead of (obsolete) IUSBController
    
    This patch is tested on Mac OS X 10.8.5 and Fedora 19.
    
    Signed-off-by: Ryota Ozaki <ozaki.ryota@gmail.com>