NEW FEATURES:

• require(pkg, quietly = TRUE) is quieter and in particular does
  not warn if the package is not found.

DEPRECATED AND DEFUNCT:

• Use of ftp:// URIs should be regarded as deprecated, with
  on-going support confined to method = "libcurl" and not routinely
  tested. (Nowadays no major browser supports them.)

• The non-default method = "internal" is deprecated for http:// and
  ftp:// URIs for both download.file and url.

• On Windows, method = "wininet" is deprecated for http://,
  https:// and ftp:// URIs for both download.file and url. (A
  warning is only given for ftp://.)

  For ftp:// URIs the default method is now "libcurl" if available
  (which it is on CRAN builds).

  method = "wininet" remains the default for http:// and https://
  URIs but if libcurl is available, using method = "libcurl" is
  preferred.

INSTALLATION:

• make check now works also without a LaTeX installation. (Thanks
  to Sebastian Meyer's PR#18103.)

BUG FIXES:

• make check-devel works again in an R build configured with
  --without-recommended-packages.

• qnbinom(p, size, mu) for large size/mu is correct now in a range
  of cases (PR#18095); similarly for the (size, prob)
  parametrization of the negative binomial. Also qpois() and
  qbinom() are better and or faster for extreme cases. The
  underlying C code has been modularized and is common to all four
  cases of discrete distributions.

• gap.axis is now part of the axis() arguments which are passed
  from bxp(), and hence boxplot(). (Thanks to Martin Smith's
  report and suggestions in PR#18109.)

• .First and .Last can again be set from the site profile.

• seq.int(from, to, *) and seq.default(..) now work better in large
  range cases where from-to is infinite where the two boundaries
  are finite.

• all.equal(x,y) now returns TRUE correctly also when several
  entries of abs(x) and abs(y) are close to .Machine$double.xmax,
  the largest finite numeric.

• model.frame() now clears the object bit when removing the class
  attribute of a value via na.action (PR#18100).

• charClass() now works with multi-character strings on Windows
  (PR#18104, fixed by Bill Dunlap).

• encodeString() on Solaris now works again in Latin-1 encoding on
  characters represented differently in UTF-8. Support for
  surrogate pairs on Solaris has been improved.

• file.show() on Windows now works with non-ASCII path names
  representable in the current native encoding (PR#18132).

• Embedded R on Windows can now find R home directory via the
  registry even when installed only for the current user
  (PR#18135).

• pretty(x) with finite x now returns finite values also in the
  case where the extreme x values are close in size to the maximal
  representable number .Machine$double.xmax.

  Also, it's been tweaked for very small ranges and when a boundary
  is close (or equal) to zero; e.g., pretty(c(0,1e-317)) no longer
  has negative numbers, currently still warning about a very small
  range, and pretty(2^-(1024 - 2^-1/(c(24,10)))) is more accurate.

• The error message for not finding vignette files when weaving has
  correct file sizes now. (Thanks to Sebastian Meyer's PR#18154.)

• dnbinom(20, <large>, 1) now correctly gives 0, and similar cases
  are more accurate with underflow precaution. (Reported by
  Francisco Vera Alcivar in PR#18072.)