[R] Package updates for new versions

[Rich Shepard]

   This is a question to better my understanding of the relationship between
core R versions and packages that work with them. It's not a complaint or
criticism.

   Installed here is R-3.5.1. There are two packages that allow integration
of R and GRASS that are not yet available for 3.5.1: rpy2 and spgrass7.

   Appreciating that package maintainers have day jobs that take priority
over volunteer package maintenance, I ask only for thoughts on when copies
of those two packages _might_ be available for 3.5.1.

Regards,

Rich