Add documentation generation through Doxygen

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Print media entity flags when printing device topology

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Sort headers alphabetically

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
configure.ac: Respect CPPFLAGS from environment

Signed-off-by: Andreas Bombe <aeb@debian.org>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Add missing stdlib.h and ctype.h includes

src/mediactl.c needs ctype.h for its use of isspace().

src/v4l2subdev.c needs stdlib.h for strtoul() and ctype.h for isspace()
and isupper().

Signed-off-by: Andreas Bombe <aeb@debian.org>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Fix linking of shared libraries

When using libudev, it is actually libmediactl that uses it and not the
media-ctl executable. libv4l2subdev uses functions from libmediactl and
therefore needs to be linked against it.

Signed-off-by: Andreas Bombe <aeb@debian.org>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>