Add a new libtheora_info example program.

This program shows how to query a few version-dependent library
paramenters, such as the vendor string and maximum speed level,
and prints a summary to stdout in 'header: value' format.

I mostly wanted this as a utility to get the maximum speed level
for benchmark scripts, but thought it structuring it as an example
was better than stuffing it in tools.

It would be reasonable to extend this to return decoder parameters
like the maximum preprocessing level.

svn path=/trunk/theora/; revision=17709