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/linear-algebra/commutation_matrix.m
+++ b/scripts/linear-algebra/commutation_matrix.m
@@ -64,8 +64,8 @@
 ## @end ifnottex
 ##  is returned.
 ##
-## See Magnus and Neudecker (1988), Matrix differential calculus with
-## applications in statistics and econometrics.
+## See Magnus and Neudecker (1988), @cite{Matrix Differential Calculus with
+## Applications in Statistics and Econometrics.}
 ## @end deftypefn
 
 ## Author: KH <Kurt.Hornik@wu-wien.ac.at>