rtt's daemon gains more functions

Today I finally had some time to add functions to rtt's daemon. Reading clocks and voltages from /sys/kernel/debug/dri/{index}/radeon_pm_info is working and might be useful for overclocking in the future. Reading and setting power management options has also been implemented. The next thing to do is to add these functions to the radeon tray tools itself.

Stuff to do:

  • Fix that annoying bug when reading/writing ~/.xsessionrc
  • Add R600_DEBUG as the first "Advanced Tweak"
  • Add some checks to prevent users from setting unavailable options
  • Get over my xmlphobia and implement the whole DRI configuration stuff