Healpix-based hashing instead of a ra/dec grid. Works now accurately
also on the poles and near ra=0.
More accurate great-arc distance formula.
Updated fake catalogue script (3.1)
Added healpy to install dependencies (3.2)
Use faster ra/dec grid when safe in off-pole/off-ra-origin fields (3.3)
Replaced progressbar with progressbar-latest (3.4)
fixed warnings for very recent numpy versions (3.5)
updated manual and made nway-write-header.py more user-friendly (3.7)
added Continuous Integration builds, checking for updates (3.8)