Intermediate commit - development of SSA unrolling for FWI and FWIabc
Implementation of SSA-style unrolling for SIMD FWI and FWIABC
Unrolling on FWI gains some 4% speed-up on big test cases
I tried to be smart on FWIABC changing the inner loop order to i1 j1 k1, but it got A LOT slower
Maybe in the future I'll just copy FWI on top of FWIabc
Erik, pay attention to FWI to FWIabc copies --> check correctness!!!