Merge branch 'number_of_links' into 'master'
Correct number of links in engine_maketasks() Correctly count the number of cell->task links required and only create the necessary number given the engine policy. This fixes a bug reported by @lhausammann when testing a simple hydro + self-gravity box. It will also (very marginally) reduce the memory footprint in the purely hydro cases. See merge request !361