camera: Adds zoom property

This adds a zoom property to the RutCamera component that affects the
projection matrix by changing with the width and height of the frustum
according to a camera->zoom factor. This is now used by the editor
camera to handle zoom navigation so when we are in play mode zooming no
longer affects the depth of field effect.
rig: remove unused init_types() function

Simply removes an unused function
build: update autogen.sh

This adds a new autogen.sh that doesn't depend on gnome-autogen.sh
use AM_CPPFLAGS not INCLUDES

automake 1.14 warns about the INCLUDES variable being deprecated by
AM_CPPFLAGS so this updates rig to avoid those warnings.
build a separate rig-slave binary

Instead of having command line options for running rig in different
device modes we now build a separate rig-slave binary.
adds initial avahi service publishing support

This adds basic support for publishing a rig-slave service on the
network via the ZeroConf protocol
Add initial avahi lookup support

This adds initial support for browsing the network for rig-slaves that
the editor might want to connect to.
Adds inital protobuf-c rpc client/server support

This adds basic support for starting an protobuf-c rpc server or client
and integrating that with the glib mainloop.