Redgreengpu fix

[lukasm91]

This are most of the changes that are left in redgreen-optimized compared to the originald ev_public_merge_rebased branch.

• various small bug fixes
• memory footprint reduction fo legenndre coefficients
• small perf imrpovements (cd7a19f)
• use cuda_copy_module instead of ext_acc
• fix potential overflows at high res
• pin buffers if needed

OpenMP is best effort ... but not tested :)

[marsdeno]

Thanks for all this!
I will test, and get your work into main PR on central branch.