Make python3 the default language

[illwieckz]

The shebang still relies on python (and does not use env), maybe it already works with python3 but I haven't tested.

Since Python2 is now deprecated we must:

• check that it works with Python3
• edit shebang to use /usr/bin/env python3 instead of /usr/bin/python

Since Python2 is now deprecated we can:

• drop any Python2-ism if exist, we don't have to care about them anymore, and no one would have right to blame use for this.

[illwieckz]

For reference, after having upgraded my Ubuntu setup to 20.04 “focal” release, Python2 got uninstalled so I was not able to build the game… Fortunately I was able to reinstall Python2 but it means so many applications were ported that my own installation did not required Python2 for distro-provided packages I use.

[illwieckz]

@Viech is that something you can investigate?

[slipher]

As I recall, Viech actually originally targeted Python 3 when writing the scripts. We then requested Python 2 compatibility so that it could use the same interpreter as the NaCl toolchain. Viech expressed dismay at this requirement, but then it turned out that the code already worked in Python 2 without any modifications. (I even managed to find this conversation in my logs, but it is fairly long and noisy so I will not post it.)

[Viech]

That does sound like @Viech (who is a Python library developer these days and is still haunted by Python 2 compatibility requirements on a semidaily basis).

[illwieckz]

So, the real issue seems to be the NaCl toolchain… 😕