[xml] Fw: import tag somewhat fixed

[<rost lo-res org>]

I got asked to make this public on the list to ease further discussion, so
here we go...

> Daniel,
>
> I have fixed some part of the "import"-relevant code in xmlschemas.c. 
>
> It is now possible to import XML-schemata and reference types defined
> in these via their QNames. It is not backwards compatible insofar that the
> schemasImports hashtable of a struct _xmlSchema is now used to store
pointers
> to xmlSchemaImportPtr's instead of an xmlChar* containing the namespace's
> schemaLocation. Since the hashtable is not used outside of xmlSchemaImport
in
> the vanilla libxml2-2.6.2 version anyway I don't think I have broken
> something.
>
> Please note that it still isn't possible to lookup element declarations and
> such in imported schemata since I couldn't find the corresponding pendants
to
> xmlSchemaGetType for elements and didn't want to mess with the
> schema-independent code. Although I think that this extension shouldn't be
> much of a problem I didn't get the OK by my project leader to invest more
time
> in this, so at the moment I can just offer you the work done.
>
> I have tested the code with 'make testall' in the libxml2 root
> directory and have diffed the results against the output of a regression
test
> of a vanilla libxml2-2.6.2 version.
>
> This tar file includes:
> libxml2-2.6.2-import-types-patch   - the patch for xmlschemas.c
> regression-test-libxml-2.6.2-orig 
> regression-test-libxml-2.6.2-patched - the output of the patched and
>                                        unpatched libxml2 versions     of
>                                        'make testall'
> testImport* - a small example explaining the problem and providing a     
>               test case for the new functionality
>
> I don't know if this is enough to be included in the next stable release
which
> would make maintainance of code at my side of course more easy. If there is
> something missing please let me know so I could try to get more time on
this.
> thanks,
> Robert