Log Message:
Update R to version 1.6.1.

Pkgsrc changes:
Now builds the libR.so and provides a buildlink2.mk for packages that want
to use it.  From suggestions from Kent Polk.

Recommended library set is now included in the base package.

Changes:
               CHANGES IN R VERSION 1.6.1

NEW FEATURES

    o   Added a few "trivial and obviously missing" functions to tcltk:
        tkchooseDirectory, tkpopup, tkdialog, tkread

    o   barplot() has a new argument `axis.lty', which if set to 1
        allows the pre-1.6.0 behaviour of plotting the axis and tick
        marks for the categorical axis.  (This was apparently not
        intentional, but axis() used to ignore lty=0.)
        The argument `border' is no longer ".NotYetUsed".

                CHANGES IN R VERSION 1.6.0

USER-VISIBLE CHANGES

    o   The default colour palette now has "grey" instead of \ 
"white"
        in location 8.  See palette().

    o   grid(nx) behaves differently (but the same as in R versions <= 0.64).

NEW FEATURES

    o   Preparations for name space support:

    o   The objects created in the methods package to represent
        classes, generic functions, method definitions, and
        inheritance relations now themselves belong to true classes.  In
        particular, the "classRepresentation" objects follow the \ 
description
        in "Programming with Data" (section 7.6).

    o   Other additions and changes to the methods package:

    o   New methods ([[, print, str) and extended plot() method
        (incl. logical `horiz') for "dendrogram" class.

    o   sprintf() now checks the agreement between formats and object
        types, and handles special values (NA, Inf, ...) correctly.

    o   chol() now uses a tolerance for non-positive-definiteness and
        so should give more consistent results across platforms.

    o   New function agrep() for approximate (fuzzy) string matching.

    o   help.search() can now use both approximate (fuzzy) and regular
        expression matching.  By default, if the pattern to be matched
        consists of only alphanumeric characters, whitespace or a dash,
        approximate matching is used.

    o   axis() has three new optional arguments `col', `lty', and `lwd'
        all for drawing the axis line and tick marks.

    o   Function vcov() (formerly in MASS), a generic function to
        return the variance-covariance matrix of the parameter
        estimates of a fitted model.

    o   duplicated() and unique() have methods for matrices and arrays
        (based on ideas from Jens Oehlschl<E4>gel).

    o   Internally memory sizes and counts of cons cells are now stored
        in unsigned longs.  This allows memory limits to be set and
        objects created in the range 2-4Gb on 32-bit platforms, and
        allows 64-bit platforms to use much larger amounts of memory.

    o   Command-line flags to set memory can now use the suffix `G'
        for gigabytes.  The setting of maximum vsize is now only
        limited by the platform's address space.

    o   All warning and error messages are truncated to a length set
        by options(warning.length=), defaulting to 1000.  (Previously
        most (but not quite all) were truncated at 8192 characters.)

    o   [dpqr]gamma() check for shape parameter > 0.

    o   as.POSIX[cl]t can now convert logical NAs.

    o   All installed packages (even those shipped with R) are
        given a `Built' field in the DESCRIPTION file.

    o   as.data.frame() now coerces logical matrices into logical
        columns (rather than factors).

    o   [[<-.data.frame no longer coerces character replacement values
        to factor.  This is consistent with using $ to replace and
        with S4.

    o   library() attempts to detect improperly installed packages, so
        as from this version an installed package must have a
        DESCRIPTION file and that file must have been stamped with a
        `Built:' line (which was introduced in 1.2.0).  Under
        Unix-alikes, the platform is checked against that used for
        installation.

    o   print.factor() has new arguments `max.levels' (with a smart default)
        and `width'.  print.ordered() is no longer needed.

    o   RNGkind() has an additional option for normal random generators:
        "Inversion".

    o   data.frame() recycles factors and "AsIs" objects as well as
        atomic vectors.

    o   rect() accepts additional graphics parameters through a ...
        argument (in the same way as polygon).

    o   strwidth/strheight() now coerce their first argument in exactly
        the same way text() does, so a wider range of inputs is allowed.

    o   prompt()'s default and data.frame methods have a new 3rd argument
        `name' allowing them to used more easily in scripts and loops.

    o   rgb() has a new `maxColorValue' argument, allowing r,g,b in [0,M],
        particularly in {0:255}, efficiently and non-error-prone.

    o   summaryRprof() provides the functionality of R CMD Rprof in R
        code, though more slowly.

    o   pdf() now uses PDF not R code for clipping, which ensures that
        partially visible text strings are (partially) shown.

    o   Each R session uses a per-session temporary directory which
        is removed at normal termination.  The directory name is given
        by the tempdir() function, and filenames returned by
        tempfile() will be within that directory.

   o   help.start() on Unix now uses a .R subdirectory of the
        per-session temporary directory and not ~/.R.  A side effect
        is that ~/.R is now never deleted by R.

    o   cbind/rbind() used to ignore all zero-length vectors, an
        undocumented quirk for S-compatibility.  This caused problems
        when combining zero-extent matrices and zero-length vectors, and
        now zero-length vectors are ignored unless the result would
        have zero rows/columns.

    o   plot.spec(x) now also works for other x than AR and Pgram results.

    o   New functions La.chol() and La.chol2inv() for Cholesky
        decomposition and inverse of positive definite matrices using
        Lapack.

    o   Changes to the tcltk package

    o   New function axTicks() returning tick mark locations like axis().

    o   grid() has a more sensible default behavior.  Tick axis alignment
        only happens when no numbers of grid cells are specified.  New
        arguments lwd and equilogs; nx/ny = NA for not drawing, see ?grid.

    o   installed.packages() has a new argument `priority'.

    o   termplot() uses factor levels rather than 1,2,3... for x-axis.

    o   The trace() function has been robustified and a new function
        tracingState() added to turn tracing temporarily on and off.

    o   New cophenetic() in "mva" as utility for hierarchical clustering.

    o   p.adjust() has two new methods, 'Hommel' and 'FDR', contributed
        by Gordon Smyth <smyth@wehi.edu.au>.

    o   stars() now has add and plot arguments.

and lots of bug fixes.