* Faster range queries
This PR does several changes
- ip compact space now uses u32
- the bitunpacker now gets a get_batch function
- we push down range filtering, removing GCD / shift in the bitpacking
codec.
- we rely on AVX2 routine to do the filtering.
* Apply suggestions from code review
* Apply suggestions from code review
* CR comments
* Improvement on the scalar / random bitpacker code.
Added proptesting
Added simple benchmark
Added assert and comments on the very non trivial hidden contract
Remove the need for an extra padding.
The last point introduces a small performance regression (~10%).
* Fixing unit tests