PosUtil::assert_uppercase() becomes a macro, to avoid a warning when
compiling with -D NDEBUG. The new name is assert_uppercase(), still
defined in posutil.hh.
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.