The code now tries the following options, in order:

• obtain monitors via RandR 1.5
• obtain outputs via RandR ≤ 1.4
• obtain screens via Xinerama

fixes #159
related to #101
related to #148
related to #149

The script used to make these changes can be found at:

   https://gist.github.com/Deiz/32322020f76d23e2bf8f

From here on, we’ll use clang-format to automatically format the source.

This has worked well in i3, so we are introducing it for i3lock.

See also:
http://article.gmane.org/gmane.linux.kernel/1268792

The C compiler will handle (void) as "no arguments" and () as "variadic
function" (equivalent to (...)) which might lead to subtle errors, such
as the one which was fixed with commit 0ea64ae4.