This patch is to have clang++ (>= 3.2) happily build OwlPS Positioner.
For some reason it doesn't work on NetBSD, but it is fine on GNU/Linux
and (a couple of warnings apart) on DragonFly BSD.
Enable Doxygen option MULTILINE_CPP_IS_BRIEF, so that we don't have to
use \brief: C++-style comments are for brief descriptions and C-style
comments for extended descriptions.
Fix some comments (use @param instead of @arg).
Request::get_measurements(mac) is renamed Request::get_measurement(mac).
A Request can't store more than one measurement per AP, so it was a
mistake to return a vector. The new function returns a single pointer.
To be consistent with the other modules, the positioning server must be
called OwlPS Positioner instead of Positioning, and the executable
owlps-positionerd (even if the daemon mode is not implemented yet).
That's a big commit for a tiny change.