Revision 2352

More fixes to svgexport to make used ids unique and
conforming to XML's Name production.

* Extensions/svgexport/test/test_svgmapwriter.py: Added new tests
test_xml_id_constraints(), test_make_ide_nosetbaseid() and
test_make_id_nonintegersetid().  Switched SetID and SetBaseID.
Added Bernhard R. as author.
* Extensions/svgexport/svgmapwriter.py (make_id): Using "_" as
concatenation char now (makes test_make_ide_nosetbaseid() valid).
Also transform second id part with "%d" and catch the TypeError
to raise SVGMapWriterError (making test_make_id_nonintegersetid() ok).
Corrected typo inBernhard's author line.
(SetBaseID): Return the transformed base id. Transform characters
which are not alnum() or in ".-_" to binascii.b2a_hex(). Added
import binascii. If to be set string starts with "xml" or so, add "t".
(draw_shape_layer_incrementally): use the returned value of SetBaseID
for used_baseids checks.