also str representation of unicode character is different.

py2/py3: import InstanceDict from DocumentTemplate._DocumentTemplate instead of deprecated DocumentTemplate.DT_Util.

use urlsplit instead, prepending '//' like discussed in https://bugs.python.org/issue27485#msg270215

fixes errors on python3, File needs bytes

This not closed comment tag was probably a problem for Chameleon, this
is from a commit from Aurélien in 2021, adjusted by Jérome in 2023 (to
actually remove the code that were commented out, not just removing the
comment and leaving the code)