is, = and ==?

[Felienne]

In a discussion with @MarleenGilsing we came to the conclusion that this too might need a bit of rework. @MarleenGilsing, if I recall correctly, this was your idea:

• In current level 6 when we add calculations, change is in assignments to =
• In current level 14 where we introduce < and >, we also switch is in conditions to ==

I think in both situations we want to allow both, or give a warning but not a hard error for the use of is.

Benefits are that this save a final level with only boring "Python changes" as we had before.

What do other people think of this?

[Felienne]

Now that I implemented this change partly, the "In current level 5 when we add calculations, change is in assignments to =" part in #1504 @MarleenGilsing changed her mind slightly and wants = to be allowed in comparisons too.

Will fix this now and then work on the second bullet!

[Felienne]

This has now been implemented as planned above!