Need standard way of recording package-level roxygen3 metadata

[hadley]

• Whether or not to use markdown
• Whether or not to use autoImports
• Which roclets to run by default
• Which version of roxygen to run

The obvious place to put this information would be in the DESCRIPTION. One option would be to use a common prefix:

Roxygen-version: 2
Roxygen-markdown: false
Roxygen-roclets: namespace, collate
Roxygen-autoimports: true

Another possibility would be to create an R object:

Roxygen: list(version = 2, markdown = F, roclets = c("namespace", "collate")), autoimports = FALSE)

Since we'd control when that evaluation occurred, it could even be a nicer function:

Roxygen: roxy_options(markdown = T, ver = 2)

But that would make life a bit harder for devtools which also needs to know which version of roxygen to run.