advice from goodpractice

[corybrunson]

[The goodpractice package]() automates a number of checks and recommendations for R package developers. I just discovered it and ran it on ggalluvial, obtaining the following advice:

It is good practice to

  ✖ not use "Depends" in DESCRIPTION, as it can cause name
    clashes, and poor interaction with other packages. Use "Imports"
    instead.
  ✖ omit "Date" in DESCRIPTION. It is not required and it
    gets invalid quite often. A build date will be added to the
    package when you perform `R CMD build` on it.
  ✖ not import packages as a whole, as this can cause name
    clashes between the imported packages. Instead, import only the
    specific functions you need.

• I believe ggalluvial should keep ggplot2 under Depends, per the advice in the namespace chapter of R Packages.
• I am happy to omit Date from DESCRIPTION.
• I'm not sure how to address the third piece of advice but it does make sense and i assume will be straightforward.

[corybrunson]

This seems to be done but may be revisited.