[scribus] Scribus 1.5.6.svn, scripter and Python 3

[Jean Ghali]

Hi all,

Python 2 will soon be out of support and some distros have already started the process
which will lead to the removal of Python 2 packages from their repositories.

This took some time, but Scribus scripter has now been ported to Python 3 which means
that Scribus 1.5.6.svn now depends on Python 3 packages. Those of you using Ubuntu or
Debian derived distributions and compiling Scribus by their own will want to install the
python3-dev package in order to continue to do so. It is also recommended to install the
python3-tk package.

This changes will break lots of existing scripts due to differences between the Python 2
and Python 3 languages. Those of you relying on scripts for their tasks and using PPAs for
getting 1.5.6.svn images may want to delay further updates and use AppImages in order to
port their scripts to Python 3.

The AppImage generation process might be broken at this point tho. However if it is, it will
be fixed quickly.

Jean