WARNING:root:Annoy isn't installed about implicit

[benfred]

pip install annoy will download and install the annoy library.

I didn't specify this as a dependency, mainly because when I first tried it failed to install on windows. I agree that the last.fm example should probably fall back to the exact variant automatically if annoy isn't installed.

Also I believe windows support with annoy might work now, but I'm thinking of transitioning the approximate nearest neighbours support over to nmslib since its significantly faster.

[benfred]

I've changed to only try importing annoy right before the index is created here: #51 This warning shouldn't show up anymore. (I've also added code for nmslib/faiss as part of that PR which is worth checking out).