Generates and evolves a disc-patch, where gas is in hydrostatic
equilibrium with an imposed external gravitational force, using the
equations from Creasey, Theuns & Bower, 2013, MNRAS, Volume 429,
Issue 3, p.1922-1948.

To generate ICs ready for a scientific run:

1) Recover a uniform glass file by running 'getGlass.sh'.

2) Generate pre-ICs by running the 'makeIC.py' script.

3) Run SWIFT with an isothermal EoS, no cooling nor feedback, and the
disc-patch potential switched on and using the parameters from
'disc-patch-icc.yml'

4) The ICs are then ready to be run for a science problem. Rename the last 
output to 'Disc-Patch-dynamic.hdf5'. These are now the ICs for the actual test.

When running SWIFT with the parameters from 'disc-patch.yml' and an
ideal gas EoS on these ICs the disc should stay in equilibrium.