No tasks for empty cells

See merge request !752

Correct the condition to escape the creation of hydro tasks in the absence of feedabck in the make_hydroloop() function.

Fix typo in tracers output: Type0 and Type4 should have the same name

See merge request !751

Only set a common super-cell pointer if we are running with the policy corresponding the to the hydro/grav pointer we are looing for.

Add iact for star formation

See merge request !741

Rewrite of MPI loops - Add stellar feedback loops

Closes #522, #476, and #449

See merge request !745

Fix the random number generator

See merge request !742

Add more critiria to check if the numbers are random and also complete the correlation between different processes

Merge branch 'mpi_stars2_matthieu' of gitlab.cosma.dur.ac.uk:swift/swiftsim into mpi_stars2_matthieu

Added a force-communication with its dependency on the drift to make sure the data is correctly drifted before being received in the star loop.