+ Debian Bullseye uses python3
+ libapache2-mod-python is ported to python3 on Bullseye, but segfaults
+ libapache2-mod-wsgi-py3 is present on Stretch, Buster, Bullseye
+ adapted handler script and apache2 config to mod_wsgi api
+ mod_wsgi doesn't support setting a handler for .isl suffix as mod_python did,
I found it easier to handle png files (e.g. fire animation) in our handler than
to mingle with apache2/wsgi configuration
+ apache2 config: use modern "Require" keyword
+ TODO: commmented out some logs in handler
+ TODO: rewrite rules in config doesn't work anymore and are commented out

+ logging to /opt/szarp/logs is deprecated

* Changed variable name

* Configuration files need to have *.conf extension,
* Some additional permission features in site szarp configuration.

* Added custom XSLT function for URL retriving
with proper error handling and logging problems.