…reduction type is changed

… legacy zero helper function

…ternal computation

…oduce new CMake set types: real_t (QUDA_SCALAR_TYPE) - the host side scalar precision, complex_t the complex version of this (replaces Complex), device_reduce_t (QUDA_REDUCTION_TYPE). Eventually we will be able to set these to non-double types, but we're there yet....

…done)

…educe_t are different types, e.g., double vs doubledouble

… a different type (needed when copying from deviation_t<doubledouble> to deviation_t<double> for example

…ble (need to split into 64-bit words) and small generic cleanup

…so updates the coalesced writing to sysmem to work with large reduce_t types, such that sizeof(device_reduce_t) / sizeof(atomic_type<device_reduce_t>) > warp_size, which previously was a restriction: we now use a warp-stride loop to do a coalesced write to sysmem

…MP at present and just a simple gather method for now

…to real_t done after the multi-process reduction

…r direct comparisons, use max error not error sum when multiple norms are used to check correctness, print out the deviation when verbosity >= QUDA_VERBOSE

…itations representing this being WIP (bin bounds LUT repeatadly recomputed on the host, bin bounds LUT presently in explicit constant, CG reduction not supported, warp reductions rather register heavy, etc.)

…to feature/reproducible

…nction)

… variables (remove bad cast)

…lizing the reduction. All tests passing, but seemingly break when a SANITIZE build is used

…to feature/reproducible