Keep argument descriptions together when inheriting

[thomasp85]

When several arguments are documented together (@param x,y ...) and this argument is inherited in another markdown chunk with @inheritParams the arguments are split up instead of kept together. Keeping them together in instances where it is possible would make param inheritance more useful

[IndrajeetPatil]

Same issue as #826

[gaborcsardi]

We will fix this, but it will not make it into 7.0.0, which is already happening. Sorry!

[thomasp85]

is there any plans of adding this or has it ended up being a wontfix?

[hadley]

I think we'd still like to fix this one day; it comes up in quite a few places.