VirtualBox 4.3.0 RC1

# The following major new features were added:
* VMM: major rewrite of the VT-x code and the AMD-V code including many bug fixes and performance improvements
* VMM: introduced a lightweight instruction interpreter for situations not handled by hardware virtualization
* GUI: extended messaging mechanism (new non-modal popup overlays used to show noncritical warnings and provide user with additional information)
* GUI: keyboard shortcuts management (input page of global preferences extended with possibility to edit general keyboard shortcuts for VirtualBox Manager and Virtual Machine)
* GUI: video capturing support
* Added USB touch device emulation
* Added SCSI CD-ROM emulation, including boot support
* VRDP: support for IPv6
* Guest Control: guest sessions now are running in dedicated, impersonated session processes (needs at least Guest Additions 4.3 installed)
* Guest Control: implemented IGuestFile support
* NAT: experimental virtual router mode: several VMs are attached to the same internal network and share one NAT service
# In addition, the following items were fixed and/or added:
* VMM: significantly improved performance of NetWare 5.x/6.x guests on host systems without nested paging support
* VMM: fixed losing host NMIs while in VT-x guest-context
* VMM: changed order of actions in emulated task switch
* GUI: update check uses https
* GUI: numerous minor internal cleanups and bug fixes
* GUI, VBoxManage: when unregistering a VM, also unregister the hard disk images which are used exclusively
* GUI: use the number of physical presented processor cores instead of the number of logical processor cores to check if the users assigned too many virtual CPUs to the guest
* Snapshots: made live snapshots work again
* Teleportation: made it work again
* Storage: implemented AHA-154x compatibility mode in the emulated BusLogic SCSI HBA
* Storage: significantly improved performance of large ATAPI PIO transfers (BeOS, Minix 3 guests affected)
* Storage: added floppy formatting emulation (NB: cannot be used to change existing media geometry)
* Settings: global and per-VM default frontend configuration, useful to select the use of alternative VM frontends
* Settings: limit depth of snapshot tree to 250 levels, as more will lead to decreased performance and may trigger crashes
* Settings: the per-VM hwvirtextexcl setting has been replaced by a global hwvirtexclusive property
* Main: new event queue implementation which does not use the host’s native event queue for processing VirtualBox events anymore
* Main: eliminate the use of SysV semaphores on all host OSes other than Windows, namely Linux, Solaris and Mac OS X, with the consequence that no system reconfiguration is needed to run more than approximately 100 VMs
* Main: use the XDG standard configuration folder instead of .VirtualBox on systems where it is appropriate
* Main: extension pack framework can now support loading HGCM modules
* VBoxManage: list more information about hard disk/DVD/floppy media, and support the --long option to show really all available details
* VBoxManage: added support for optional command line parameters for the automatic Guest Additions update
* VBoxManage: added support for listing active guest sessions, guest processes and/or guest files via guestcontrol list <all|sessions|processes|files>
* VBoxManage: added support for closing active guest sessions via guestcontrol session close --session-id <ID>| --session-name <name or pattern>|--all
* VBoxManage: added support for terminating active guest processes via guestcontrol process kill|close|terminate --session-id <ID>| --session-name <name or pattern> <PID> ... <PID n> or guestcontrol [p[s]]kill --session-id <ID>| --session-name <name or pattern> <PID> ... <PID n>
* VBoxManage: added support for watching guest sessions via guestcontrol watch
* 3D support: several fixes
* 3D support: several fixes for Mac OS X hosts
* OVF: several fixes
* Extpack Installer: make it work if the file is located in a folder with special characters
* Keyboard: fix for reporting key sequences like Ctrl+Alt+Del for the USB keyboard emulation
* Shared Clipboard/X11: support for BMP-format images, contributed by François Revol
* Windows hosts: don’t cause massive DPC latency (only on certain hosts; still needs improving)
* Windows hosts: consider symlinks when retrieving volume information
* Windows hosts: fixed an issue with USB2 devices being inaccessible when plugged into USB 3.0 ports
* Windows Additions: fixed misbehavior with guest display power management (WDDM driver only)
* Windows Additions: fixed memory leak caused by WTSQuerySessionInformation() on Windows 2000 guests
* Linux Additions: fixed udev detection in the init script with Linux 3.x kernels
* Windows guests: ability to track guest user idle times through the newly introduced event IGuestUserStateChangedEvent