Add configurable loss clipping.
Add max_loss argument.
Reduce default value of max_loss, update docstrings.
Merge pull request #26 from maciejkula/clip_loss

Clip loss at maximum value
First working version of out-of-core co-occurrence matrix construction.

Uses memmapped numpy arrays.
Cleanup of the memmap-based approach.
Add pre-shuffling of the co-occurrence matrix.
Note that matrix is shuffle in-place in docstring.
Clean up, update comments.
Add docstring to COOMatrix.