doc: spellcheck of documentation before 3.8 release. * doc/interpreter/doccheck/aspell-octave.en.pws: Add new words to Octave-specific dictionary. * libinterp/corefcn/ellipj.cc, scripts/image/imfinfo.m, scripts/miscellaneous/copyfile.m, scripts/miscellaneous/movefile.m, scripts/plot/meshgrid.m, scripts/specfun/expint.m: spellcheck of documentation before 3.8 release.

--- a/scripts/specfun/expint.m
+++ b/scripts/specfun/expint.m
@@ -60,7 +60,7 @@
 ## @end example
 ##
 ## @end ifnottex
-## The two definititions are related, for positive real values of @var{x}, by
+## The two definitions are related, for positive real values of @var{x}, by
 ## @tex
 ## $
 ## E_1 (-x) = -{\rm Ei} (x) - i\pi.