submit 0.5.0 to CRAN

[matthewcornell]

2020-04-08: All checks pass (!), but the final devtools::submit_cran() call fails with this error:

Uploading package & comments Confirming submission Error in if (new_url$query$submit == "1") { : argument is of length zero

I'm hoping for a reply to submit_cran() errors confirming submission: "argument is of length zero" . O/w I'll try submitting manually:

• http://r-pkgs.had.co.nz/release.html#release-check
• https://cran.r-project.org/
• https://cran.r-project.org/submit.html
• ...