Add spellchecker scripts for Octave and run spellcheck of documentation interpreter/doccheck: New directory for spelling/grammar scripts. interpreter/doccheck/README: Instructions for using scripts. interpreter/doccheck/spellcheck: Script to spellcheck a Texinfo file. interpreter/doccheck/aspell.conf: GNU Aspell configuration file for Octave documentation. interpreter/doccheck/aspell-octave.en.pws: Private Aspell dictionary. interpreter/doccheck/add_to_aspell_dict: Script to add new Octave-specific words to private Aspell dictionary. interpreter/octave.texi: New @nospell macro which forces Aspell to ignore the word marked by the macro. interpreter/mk_doc_cache.m: Skip new @nospell macro when building doc_cache.

--- a/scripts/special-matrix/hadamard.m
+++ b/scripts/special-matrix/hadamard.m
@@ -25,7 +25,7 @@
 ## Construct a Hadamard matrix @var{Hn} of size @var{n}-by-@var{n}.  The 
 ## size @var{n} must be of the form @code{2 ^ @var{k} * @var{p}} in which
 ## @var{p} is one of 1, 12, 20 or 28.  The returned matrix is normalized,
-## meaning @code{Hn(:,1) == 1} and @code{H(1,:) == 1}.
+## meaning @code{Hn(:,1) == 1} and @code{Hn(1,:) == 1}.
 ##
 ## Some of the properties of Hadamard matrices are:
 ##