Add hdf5 subfind script forgotten earlier
Fixed periodic box conditions in halohi

Conflicts:
	halohi.py
Fixed bug in halohi where we crashed if no gas in halo
Move sigma_DLA to the PrettyHalo class
Quick plot to make mean mass-weighted metallicity
Fix bug
Another routine for working with snapshots
Split the halo finding routine into a separate module
Use density threshold in physical density, not comoving
Some comments about comoving vs physical units
Comments again
Add function to just use the values from Arepo
Use the hydrogen mass fraction from the code, instead of primordial abundance
Use code HI fraction
Update comments
Allow the gas or HI density to be null, ie, obey skip_grid even when the
grid is generated for the first time
Add class for computing metal densities rather than HI densities
Function for computing absorber fractions
Do not generate a gas grid for the whole box
Implement periodic grids in fieldize, and enable them for BoxHI