5.9 or 6.0 Release

[bjpalmer]

This is a checklist for the next post-5.8 release. The major outstanding issue for this release is getting the GPU-aware functionality in the PR branch to work with multiple PRs on one SMP node. The following branch has an outstanding pull request

-[ ] feature/ga-lu-fix

The remaining PRs may have stalled out or been incorporated into the code via other work-arounds. Other branches that currently exist are

-[ ] feature/ga-sparse
-[ ] feature/ga_cxx
-[ ] feature/cuda
-[ ] feature/cuda-debug-2
-[ ] feature/offset