improved dispatching to built-in classes

[John W. Eaton]

On 12-Jan-2010, Jaroslav Hajek wrote:

| the following changeset rewrites some parts of the dispatching
| mechanism for built-in classes to make Octave's behavior more
| Matlab-compatible:
| http://hg.savannah.gnu.org/hgweb/octave/rev/090173f2db40
| 
| Previously, in absence of user classes in the argument list, Octave
| always used the class of the first argument for dispatching. This is,
| however, not what Matlab does - in Matlab, some built-in types are
| preferred over others, so in case of multiple arguments the dispatch
| type could differ significantly.

OK, I think part of the reason that this wasn't done before was that
(as you say) it doesn't appear to be documented anywhere.  The only
thing I can remember seeing is that classes have precedence over user
defined types.

In any case, thanks for working on this and for creating a
comprehensive test script.

jwe