We might hope to be clean against all the issues it identifies

Just uses abort() instead of exit() in non-MPI code

Removed old interaction debugging option and created a new one that is not associated with an SPH scheme.

Also detect whether the current POSIX implementation offers the optional function posix_fallocate(). If not, switch off the particle streamed logging.

Implement simple thread barriers to be used on systems where the POSIX implementation does not provide them. We default to the POSIX ones when detected at configure time.

Force compiler to report shadowed variables. Removed all shadowed variables. Added the function scheduler_activate_send() to simplify the unskipping of MPI sends.

Removed redundant tests from test suite. testPair.sh and testPairPerturbed.sh superceded by test27cells.sh and test27cellsPerturbed.sh. Added new testActivePair.sh that tests dopair1 when the number of active particles is varied.

Updated version number to 0.6.0 to reflect the large number of changes to the threadpool, drifts, MPI and scaling performance in the last few months.

Removed redundant tests from test suite. testPair.sh and testPairPerturbed.sh superceded by test27cells.sh and test27cellsPerturbed.sh. Added new testActivePair.sh that tests dopair1 when the number of active particles is varied.

This reverts merge request !375

Corrected mistake in the periodic boundary test that prevented compilation when optimisations are switched off.

Make the difffloat script use a new line in the files to set a limit below which values are ignored as too close to zero.