Improve formatting of inheritDotParams

[halldc]

Fixes #730

That is, improve formatting for @inheritDotParams tag:

• Add link to function
• Wrap params in \code{}

[gustavdelius]

This works very nicely.

[gustavdelius]

In new versions of R, the use of boolean vectors in if statements is deprecated and issues a warning ". Therefore you may want to replace your is.na(pkgs), which produces a boolean vector if pkgs is a vector by anyNA(pkgs).

[hadley]

Could you please use expect_known_output() to construct a small test that demonstrates how the new rendering looks?

[hadley]

Thanks @halldc!