* progmodes/octave.el (octave-font-lock-keywords): Handle 'end' in

* progmodes/octave.el (octave-font-lock-keywords): Handle 'end' in
indexing expression.
(octave-continuation-string): Do not use \.
(inferior-octave-complete-impossible): Remove.
(inferior-octave-completion-table)
(inferior-octave-completion-at-point): Remove its uses.
(inferior-octave-startup): completion_matches was introduced to
Octave in 1996 so safe to assume it.
(octave-function-file-comment): Improve to follow how Octave does it.
(octave-update-function-file-comment): Tweak.