Support for libcaca terminal

[Pierrick Bouvier]

Dear maintainer(s),

we would be interested in having support for libcaca backend, making 
text output more colored than it is now:

$ cat script.plot
set terminal caca # instead of dumb
...

Would that be acceptable to add it to the official package?
Normally a simple --with-caca added to configure should be enough.

Thanks,
Pierrick