Add LXC version information to version.h

So that applications can get the LXC version number at compile time.

This can be used to make applications/bindings that support compiling against
multiple versions of LXC.

Signed-off-by: S.Çağlar Onur <caglar@10ur.org>
Acked-by: Stéphane Graber <stgraber@ubuntu.com>
Reduce public API (V2)

This removes all but the following headers from our includes:
 - attach_options.h
 - lxccontainer.h
 - version.h

This also removes the duplicate lxc_version function (lxc_get_version
has been preferred for a while).

lxclock.h is now considered private.

As a result quite a lot of files needed addition of extra includes
previously inherited from lxclock.h.

Signed-off-by: Stéphane Graber <stgraber@ubuntu.com>
Acked-by: Serge E. Hallyn <serge.hallyn@ubuntu.com>