falconn wrapper

[VarIr]

Currently, there seems to be no way to create a valid scikit-learn-compatible wrapper for falconn, as its LSHindex cannot be pickled. This is an issue of falconn.

Possible solutions:

• Wait for falconn pickle support (however, no ETA)
• Switch to different LSH library
• Add other ANN tools, be it LSH or not

[VarIr]

The falconn.LSHindex could possibly be memmapped as done in #21.

[VarIr]

There seems to be no adequate way to serialize/memmap the index. falconn development seems to have stalled, so it's unclear, whether this will be possible at all.

[VarIr]

puffinn can now pickle its index, so phasing out falconn is probably the way to go.