Comment 7 for bug 187449

here's a new patch doing the 'magic namespace'.

here's how it works:
add a new attribute to SPXMLNs: bool is_custom
the namespaces from repr-util.cpp are the standart ones, those added by sp_xml_ns_uri_prefix are custom ones.
(new function sp_xml_ns_is_custom to test if a prefix belongs to a custom one.)

when doing a bool operation or converting an object to path, it uses the sp_copy_custom_attributes function which copy the attributes from custom namespaces to the new object.

the sp_copy_custom_attributes function has been added to the repr-util.cpp file.

diff genrated with:
gorse@gorse-desktop:~/bordel/inkscape-0.47-svn/inkscape$ svn diff -x -u > custom_attr_namespace.diff
from svn 21209.