BIG BUG in my all to all optimization code

[sebjameswml]

The code currently in master since I merged my alltoall_optim branch has a numerical bug!!! Need to find this soon.

[sebjameswml]

This means, DON'T use the master branch at present. Use safe_from_alltoalloptim instead until this is resolved.

[sebjameswml]

All to all optimisation disabled in master with commit fd55e20. I've now got the code fixed as well, but need to finalise the changes in the xsl.