Version 3.1 - 25 February 2013

Highlights:
- [new] Support for primus as an alternative to virtualgl as optirun back-end.
  Added a new Bridge option in bumblebee.conf to set the default back-end (auto
  as default currently, selects VirtualGL if installed, else primus, detection
  order may change in 4.0). optirun gained a -b/--bridge option for on-the-fly
  back-end choice.
- [enhancement] Use of non-blocking sockets, replacing former 3.0.1 hotfix for
  socket polling.
- [enhancement] Added an udev rule to fix nvidia card randomly turning on.
- [fix] Fixed the three remaining compilation warnings.
- [fix] A little fix for Kepler generation cards was added in xorg.conf.nvidia.
- [fix] A little fix for dual nvidia hybrid systems.
- [fix] Fixed nouveau not working under X.org 1.13+.
- [fix] Upstart dependencies changed to fix some issues
- [fix] Fixed available drivers detection by supporting module aliases.

Notes:
- bbswitch is independent of the driver; vga_switcheroo works for nouveau only.
  See also the Known Issues section above and
  https://github.com/Bumblebee-Project/Bumblebee/wiki/Comparison-of-PM-methods
- the video drivers must be unloadable. This means that it should not be
  compiled into the kernel. When using dynamically built modules like nvidia,
  be sure that the toolchain used for building the kernel matches the one that
  is used for building the module. This means that Ubuntu mainline kernels do
  not work and will cause crashes.
- VirtualGL performance is very dependent on the Transport method set. The
  default "proxy" setting appears to perform bad in some situations. Try other
  available settings like "rgb" or "yuv".
- Do not combine power management methods (i.e. bbswitch with the deprecated
  acpi_call), it does not save more power and will break your machine.
- primus is supposed to result in better performance, but is not compatible with
  all programs supported by virtualgl, hence virtualgl is preferred when
  auto-detecting the backend.

Known issues:
- vga-switcheroo won't survive suspension/hibernation (patch for newer Optimus 
  machines for OFF to work has been published in Kernel 3.3; a good patch for 
  suspend is still being prepared).
- bbswitch (and acpi_call) cannot disable the discrete nvidia card for the Dell
  Vostro 360 desktop with Synergy. If you have a machine using that technology,
  please submit your machine information on: 
  https://bugs.launchpad.net/bugs/752542
- Some laptops (mainly Lenovo) are neither supported by bbswitch nor the video 
  drivers. See https://github.com/Bumblebee-Project/bbswitch/issues/2