Migration from blockly 2016 to latest

[bjost2s]

From the beginning in 2014 until today, we have only managed to update to the latest Blockly once in 2016. The reason for this is that we have made a lot of changes to make Blockly suitable for our purposes.
Now our Blockly version is so old that we can expect it to no longer be fully supported by browsers. So an update is very important!

Fortunately, Blockly has put a lot of effort into becoming an easy-to-use framework for graphical programming blocks. Here are some "new" features:

• Python 3 compatibility
• no Closure Compiler anymore!
• TypeScript
• Themes
• Extensions
• ...

Here is an interesting overview about the block's definition over the years
Here is a branch from my work (4 years ago) where I have started an update