In MATLAB, if you save a binary file, it automatically is given the
extension .mat, and likewise the extension is appended before a load.
In Octave, no file extension is assumed. I think it would be convenient,
and also more Matlab compatible, to have this possibility in Octave as
well. It could pertain to mat-binary files only, or maybe to other
formats as well (with different extensions). It should moreover be
optional, because I'm sure some people in the Unix world won't like it...