R package generator improvements + async support (#1048)
R package generator improvements + async support (#1048)

* :sparkles: async/dynamic support in R pkg deps

* :hocho: remove Authors block

* :hocho: insert package version number

* :hammer: use verbose :package: title and desc from YAML

* :sparkles: autodetect vignettes

* check for author/maintainer address

* :hand: halt processing if fatal errors found

* autopopulate KeepSource

* auto-escape % in docstrings

* :hocho: filter examples from docstrings in R
plotly/dash,plotly/dash,plotly/dash,plotly/dash,plotly/dash