libqtest: Convert macros to functions and clean up documentation

libqtest.h provides a number of shortcut macros to avoid tests feeding
it the QTestState they operate on. Most of these can easily be turned
into static inline functions, so let's do that for clarity.
This avoids getting off-by-one error messages when passing wrong args.

Some macros had a val argument but documented @value argument. Fix this.

While touching things, enforce gtk-doc markup for return values and for
referencing types.

Signed-off-by: Andreas Färber <afaerber@suse.de>
Signed-off-by: Andreas Färber <afaerber@suse.de>
Message-id: 1361051043-27944-2-git-send-email-afaerber@suse.de
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
