Make the new task synchronize the particles hit by feedback and force them to recompute a time-step. Propagate the time-step upwards.

Better level for the time-step limiter task to make sure the gravity and hydro steps are synchronized.

Version that correctly flags the BHs to swallow and removes them before dying in the time-step calculation function.

Split the star formation task into two parts: The star formation bit and the resorting bit. Move the sf_count communication to just depend on the first one in order to speed things up.

entry is a very generic name and it clashes with a struct in the search.h header

Revert "Activate star tasks also if we are running with SF on and the cell is active for hydro purposes."

This reverts commit 8a1c735c.

Added communication functions to propagate the new number of star particles after a SF event has occured.

Mark the flags `volatile`, just to be safe. This is not a problem now, but I would hate it to become one later.