[Rd] API updates for R 4.6.0

[iuke-tier@ey m@iii@g oii uiow@@edu]

The installed C header files for R 4.6.0 should now correspond to the
C API as defined by the Writing R Extensions manual: All entry points
and variables declared in the headers are now part of the API.  This
helps clarify the interface available to package developers, and
provides the encapsulation needed to allow improvements to internals
of R without impacting packages. Many thanks to package developers who
helped in developing new API features to make this possible and who
worked on moving away from using non-API features.

A small number of packages with significant reverse dependencies have
not yet completed the transition. CRAN will be hosting transitional
versions for these until their maintainers submit updates.


Best,

luke

-- 
Luke Tierney
Ralph E. Wareham Professor of Mathematical Sciences
University of Iowa                  Phone:             319-335-3386
Department of Statistics and        Fax:               319-335-3017
    Actuarial Science
241 Schaeffer Hall                  email:   luke-tierney using uiowa.edu
Iowa City, IA 52242                 WWW:  http://www.stat.uiowa.edu