[xml] Error handling with the XmlReader API

["Stéphane Bidoul" <stephane bidoul softwareag com>]

Hi Daniel,

On the same error handling theme, I think
we need a specific error handling API associated with
the XmlReader interface.

Currently, I use the global error handler 
(libxml2.registerErrorHandler), but that's far
from perfect; in drv_libxml2, for instance, it
is a limitation (only one sax driver can be active 
at a given moment).

In .NET, that's easy, they have exceptions...

What's your opinion on this?
Would you see a callback interface 
or something like getLastError()?

-sbi