New logic for macro handler resolution

[Hannes Wallnoefer]

Heads up: I just committed a change to the skin macro resolution
process supposed to fix the problems introduced by the fix for bug 617
<http://dev.helma.org/bugs/show_bug.cgi?id=617>

The new resolution logic looks like this:

* resolve against the this-object prototype name, including
extended prototypes
* resolve against the res.handlers collection
* resolve against the parent path of the this-object, including
extended prototypes.

This is what I proposed under the moniker "multi-layered approach" in
this thread: <http://groups.google.com/group/helma/browse_frm/thread/
b15805fd6f661d64>

Please test user helma apps and let me know if something's broken.

Hannes