Preesm 3.8.0 and Spider 1.4.0

We have released Preesm version 3.8.0 and Spider version 1.4.0. Among all changes, we want to emphasize the new code generators in Preesm for MPPA and Hardware accelerators as well as Spider API update to support them. The Spider API update also comes with new headers to include. Complete list of changes are available in the respective release notes of Preesm and Spider.