- update math/R to 2.15.0, and adjust dependent ports
- minor changes to bsd.cran.mk [2]: rename MASTER_CRAN_SITES to
MASTER_SITE_CRAN, as in bsd.sites.mk; make the install target more
flexible and allow CRAN ports to override it; add a regression-test
target; set USE_FORTRAN to match math/R; remove some of the
redundant checks of USE_R_MOD; honor NOPORTDATA and NOPORTDOCS
Reviewed by: thierry, tota, wen
Approved by: D. Rue (maintainer) [1], wen [2]