Use drawio tree to create nice looking tree

[SmallJoker]

Alternative to #37

[orwell96]

This looks of course much better than my tech tree drawing, but:

• Clipping the image should work
• It looks for me like the image doesn't resize properly on 5.0.1

I think, if we can get this into a working state, it would be better, but we should rebase it on my work because I corrected some dependencies.

[SmallJoker]

Clipping the image would work using style[] which is 5.1.0-dev or newer, same as real coordinates that are now implied by formspec version 2.