Updated vectorisation tests



See merge request !134

Updated vectorisation tests



See merge request !133

Engine exchange strays

Tested this locally with and without MPI. Didn't actually test sending around gparts, because we can't really deal with them quite yet.

See merge request !117

Conflicts:
	src/engine.c
	src/engine.h
	src/part.c
	src/part.h
	src/proxy.h
	src/scheduler.c

This reverts commit 4ab23609

Redistribute fixes



See merge request !131

Redistribute fixes

Fixes #130 and makes `engine_split()` work for gparts.

That lead to some issues in common_io.c but the master works if you don't run with -g. (And -g does not work beyond one time-step anyway as we don't have the MPI communications for gparts yet.)

See merge request !130