Start of 0.9.x devel cycle

Start of 0.9.x devel cycle

v4l-utils follows the classic odd unstable / even stable release numbering,
this is the start of a new 0.9.x dev cycle leading to a 0.10.x (or maybe a
1.x) release. The plan for 0.9.x is to:
1) Keep the libv4l1 and libv4l2 ABI's compatible with 0.8.x
2) Change the libv4lconvert ABI, changing the soname to libv4lconvert.so.1
   (from libv4lconvert.so.0), this is needed to be able to add plugin
   support to libv4l2
3) Allow for somewhat more adventurous changes, until later in the 0.9.x
   cycle, when things should stabilize again

Note WRT 2), that there is no promise of a stable libv4lconvert.so.1 ABI
until 0.10.0 is released!

Signed-off-by: Hans de Goede <hdegoede@redhat.com>