Summary:
Pull Request resolved: https://github.com/facebookresearch/faiss/pull/2582
A few more or less cosmetic improvements
* Index::idx_t was in the Index object, which does not make much sense, this diff moves it to faiss::idx_t
* replace multiprocessing.dummy with multiprocessing.pool
* add Alexandr as a core contributor of Faiss in the README ;-)
```
for i in $( find . -name \*.cu -o -name \*.cuh -o -name \*.h -o -name \*.cpp ) ; do
sed -i s/Index::idx_t/idx_t/ $i
done
```
For the fbcode deps:
```
for i in $( fbgs Index::idx_t --exclude fbcode/faiss -l ) ; do
sed -i s/Index::idx_t/idx_t/ $i
done
```
Reviewed By: algoriddle
Differential Revision: D41437507
fbshipit-source-id: 8300f2a3ae97cace6172f3f14a9be3a83999fb89
