title: Call xbacklight through API
body: <p>Does there exist an API for the <code>xbacklight</code> utility?</p>
  
  <p>I'd like to make a graphical frontend in either C, C++, or Python, but I can't find any documentation.</p>
  
  <p>My only guess at integration at this point would be making a call to <code>system()</code>, but I like to call libraries directly.</p>
  
  <p>Does <code>xbacklight</code> have a library interface, or do I have to just call the executable?</p>