NMSLIB Dependency

[phlobo]

pip install xmen fails for some users due to lack of nmslib binaries for their distribution.

Known workarounds to install nmslib:

1. install within a conda environment, i.e.: conda install nmslib
2. pip install --no-binary :all: nmslib
3. CFLAGS="-mavx -DWARN(a)=(a)" pip install nmslib
4. pip install --upgrade pybind11
pip install 'nmslib @ git+https://github.com/nmslib/nmslib.git#egg=nmslib&subdirectory=python_bindings'

see also: allenai/scispacy#470

If this succeeds, you should be able to run pip install xmen

Long term solution:

• Get rid of nmslib dependency and create TF-IDF indices with a more actively maintained solution