Faster compilation and sparse stuff.

Update MPI test to work with python3

Fix tests

fix gh-1540 and close gh-1541. Don't use rpath if the user didn't provid...

During opt, we remove them at first and reput them after.

This was slowing down python.

Fix for python3 following gh-1550

Mixed2

Fix tests

Use logger instead of printing. Update error message.

[WIP] Fix shape cycle

Minor change: tensor.ones and tensor.zeros can accept single integer arguments

We where casting a 64 bit ptr to 32 bit.

This was done with much help from Aaron Defazio. fix gh-1547