Use SMIE for octave-mode.

Use SMIE for octave-mode.
* test/indent/octave.m: New file.
* lisp/progmodes/octave-mod.el (octave-font-lock-keywords): Use regexp-opt.
(octave-mode-map): Remove special bindings for forward/backward-block
and octave-backward-up-block.  Use smie-close-block.
(octave-continuation-marker-regexp): New var.
(octave-continuation-regexp): Use it.
(octave-operator-table, octave-smie-op-levels)
(octave-operator-regexp, octave-smie-indent-rules): New vars.
(octave-smie-backward-token, octave-smie-forward-token): New funs.
(octave-mode): Use SMIE.
(octave-close-block): Delete.