rhub::check_for_cran()

[judith-bourque]

Taking quite a long time

[judith-bourque]

Same warnings as #97

N  checking for non-standard things in the check directory
   Found the following files/directories:
     ''NULL''
N  checking for detritus in the temp directory
   Found the following files/directories:
     'lastMiKTeXException'

[judith-bourque]

The two non-standard directories are open issues in rhub:

• NULL
• lastMiKTeXException

It seems to be a rhub issue and not specific to this package, so won't fix.