edit.m: simplify default editor when not set

[Mike Miller]

I think the attached patch addresses the problems discussed in [1] and
[2], following the solution proposed by Michael in the latter thread.
Namely, the default editor for editing files is the same as EDITOR(),
even if the user changes it with EDITOR(...).  If the user sets the
editor with the edit command (edit editor "..."), then that preference
overrides EDITOR() from then on.  Let me know if you think this will
help.

[1] http://octave.1599824.n4.nabble.com/edit-error-td4541388.html
[2] http://octave.1599824.n4.nabble.com/edit-m-and-EDITOR-td4546850.html

-- 
mike

edit-default-editor.patch
Description: Text Data