[Rd] par(mfrow = ) resets par('cex'), not reduces it (PR#13373)

[cmr.pent at gmail.com]

help(par) says:

  'mfcol, mfrow' ...

    In a layout with exactly two rows and columns the base value of
    '"cex"' is reduced by a factor of 0.83: if there are three or more
    of either rows or columns, the reduction factor is 0.66.

In reality, par(mfrow =) *resets* par ('cex'), not reduces it as
documented. To reproduce:

par(cex = 0.5)
par(mfrow = c(2, 2))
print(par('cex'))

It outputs 0.83, not 0.415 as expected.

Particularly such a behavior makes plot.ts and plot.acf effectively
ignore par('cex') value for the multivariate case. I guess there are
more situations where the documented behavior would be more
appropriate.

I'm ready to provide any additional info,
Andrey

--please do not edit the information below--

Version:
 platform = i486-pc-linux-gnu
 arch = i486
 os = linux-gnu
 system = i486, linux-gnu
 status =
 major = 2
 minor = 8.0
 year = 2008
 month = 10
 day = 20
 svn rev = 46754
 language = R
 version.string = R version 2.8.0 (2008-10-20)

Locale:
LC_CTYPE=ru_RU.UTF-8;LC_NUMERIC=C;LC_TIME=ru_RU.UTF-8;LC_COLLATE=ru_RU.UTF-8;LC_MONETARY=C;LC_MESSAGES=ru_RU.UTF-8;LC_PAPER=ru_RU.UTF-8;LC_NAME=C;LC_ADDRESS=C;LC_TELEPHONE=C;LC_MEASUREMENT=ru_RU.UTF-8;LC_IDENTIFICATION=C

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