doc: Periodic spellcheck of the documentation. * doc/interpreter/doccheck/aspell-octave.en.pws: Update Octave-specific Aspell dictionary. * doc/interpreter/contrib.txi, doc/interpreter/errors.txi, doc/interpreter/expr.txi, doc/interpreter/io.txi, doc/interpreter/preface.txi, doc/interpreter/sparse.txi, doc/interpreter/stmt.txi, doc/interpreter/strings.txi, libinterp/corefcn/qz.cc, libinterp/dldfcn/ccolamd.cc, libinterp/dldfcn/fftw.cc, libinterp/interpfcn/graphics.cc, scripts/general/structfun.m, scripts/image/ind2rgb.m, scripts/image/rgb2ind.m, scripts/io/importdata.m, scripts/linear-algebra/duplication_matrix.m, scripts/linear-algebra/housh.m, scripts/miscellaneous/mkoctfile.m, scripts/plot/comet3.m, scripts/plot/gco.m, scripts/plot/legend.m, scripts/plot/print.m, scripts/signal/fftshift.m, scripts/signal/periodogram.m, scripts/sparse/pcg.m, scripts/statistics/tests/f_test_regression.m, scripts/statistics/tests/t_test_regression.m, scripts/strings/strjoin.m, scripts/strings/strsplit.m: Correct spellings or add @nospell macro.

--- a/libinterp/interpfcn/graphics.cc	Sun Jun 23 14:15:42 2013 -0300
+++ b/libinterp/interpfcn/graphics.cc	Sun Jun 23 12:49:53 2013 -0700
@@ -9925,7 +9925,7 @@
 A string property.  @var{arg} contains the default string value.\n\
 \n\
 @item any\n\
-An un-typed property.  This kind of property can hold any octave\n\
+An @nospell{un-typed} property.  This kind of property can hold any octave\n\
 value.  @var{args} contains the default value.\n\
 \n\
 @item radio\n\