Draft: Sink MPI: Let's add the physics

In this MR, I implemented the MPI sink tasks.

@matthieu @jdavies, here is the MR for the sink MPI. I'm starting from scratch, but here we can interact about the MPI, and you can follow my progress.

TODO

• Implement sink formation
• Implement sink self/pair tasks (density, swallow, do_gas_swallow and do_sink_swallow)
• Separate SF sinks from SF
• Make everything work
• Debug
• Update the doc
• Take care of gpart data access in the Basic model

examples/SinkParticles/HomogeneousBox/mpi_run.sh

+#!/bin/bash
+
+# make run.sh fail if a subcommand fails
+set -e
+
+n_ranks=${n_ranks:=2}  #Number of MPI ranks
+n_threads=${n_threads:=1}  #Number of threads to use
+level=${level:=5}  #Number of particles = 2^(3*level)
+jeans_length=${jeans_length:=0.250}  #Jeans wavelenght in unit of the boxsize
+
+#Create the ICs if they do not exist
+if [ ! -e ICs_homogeneous_box.hdf5 ]
+then
+    echo "Generating initial conditions to run the example..."
+    python3 makeIC.py --level $level -o ICs_homogeneous_box.hdf5 --lJ $jeans_length
+fi
+
+
+# Get the Grackle cooling table
+if [ ! -e CloudyData_UVB=HM2012.h5 ]
+then
+    echo "Fetching the Cloudy tables required by Grackle..."
+    ./getGrackleCoolingTable.sh
+fi
+
+
+if [ ! -e POPIIsw.h5 ]
+then
+    echo "Fetching the chemistry tables..."
+    ./getChemistryTable.sh
+fi
+
+
+# Create output directory
+DIR=snap #First test of units conversion
+if [ -d "$DIR" ];
+then
+    echo "$DIR directory exists. Its content will be removed."
+    rm -r $DIR
+else
+    echo "$DIR directory does not exists. It will be created."
+    mkdir $DIR
+fi
+
+printf "Running simulation..."
+
+mpirun -n $n_ranks ../../../swift_mpi --pin --hydro --sinks --stars --self-gravity --feedback --cooling --sync --limiter --threads=1 --verbose 0 params.yml 2>&1 | tee output.log
+
+#Do some data analysis to show what's in this box
+python3 plot_gas_density.py -i 282 -s 'snap/snapshot'
+python3 rhoTPlot.py -i 282 -s 'snap/snapshot'
+python3 rhoTPlot.py -i 0 -f 282 -s 'snap/snapshot'
+python3 plot_gas_density.py -i 0 -f 282 -s 'snap/snapshot'