Numerically motivated maximal distance for the gravity proxies and better calculation of the upper-bound.

Traced the bug back to the splitting condition in scheduler_splittask not being symmetric because of rounding

fix memory error in testSelectOutput

See merge request !600

Tag only supercells

See merge request !595

Use git to enumerate the .c and .h files that are under control, otherwise we fail when temporary .h files are also formatted (version_string.h)

Also tag all top-level cells with foreign partners, do the multipole exchange after maketasks so that we have all the necessary tags available

Add some additional checks as well

Add testFormat

See merge request !599

Handle pipe errors more explicitly, failing at first command in the pipe was OK for automation, but not very informative when ran interactively

It is SWIFT not Swift

Add a glass making master option

See merge request !598

Conflicts:
	src/engine.c

Conflicts:
  src/cell.c
  src/engine.c

Use MPI communicators to reduce the use of tags.

See merge request !591