[opus] opus-tools resampler

[Sherief Farouk]

Hi, 

	I've noticed that the opus-tools is using a really old version of Speex's resampler code - a version that I've seen fail in the wild first-hand under low resource circumstances. I've actually submitted patches for some issues in the Speex resampler a while ago (and IIRC they were accepted): http://lists.xiph.org/pipermail/speex-dev/2009-November/007541.html , http://lists.xiph.org/pipermail/speex-dev/2009-November/007542.html , http://lists.xiph.org/pipermail/speex-dev/2009-November/007525.html . 

Is there any chance the resampling code could be spun off into a separate library? A commercial-license-friendly resampler would be really helpful (I needed one myself), and a single unified library would make it a lot easier to track updates and patches. I've spun off the resampler parts some time ago when I was working on a project that relied on the Speex resampler, and it can be found here: https://bitbucket.org/sherief/speex-resample . Whether someone wants to use that as a basis of a resampler library or do a clean spin-off off of Speex's code is fine by me - I'd just like to have a single, permissively licensed resampler library tested on a variety of platforms and under a variety of conditions. I only target Windows, OS X and a Clang-based embedded platform but so far the version I have has been working fine for me. 

		- Sherief