Update kojo lab

[lego-eden]

This is a pull request meant to close issue #898. So far the syntax has been updated, and the references to kojo desktop have been removed, however somewhat clunkily. I feel like some of the tasks have too be updated further to replace the original kojo-desktop ones. For example the extra-task about experimenting with color previously expected you too use kojo-desktop's built in color picker, which is not available to us in the repl.

[bjornregnell]

There is a colorpicker in javax.swing - and it is exposed in introprog-scalalib here:

https://github.com/lunduniversity/introprog-scalalib/blob/master/src/main/scala/introprog/Dialog.scala#L61

Perhaps you can use that and update your PR. Or do you want me to merge this for now and then you create issue(s) on colorpicker and other improvements? @lego-eden

[lego-eden]

I think that would require updating the kojo.scala file to also export the color picker from introprog scalalib

[bjornregnell]

Well, we could just copy paste the def directly intokojo.scala so we don't need to add another dependency. Could you update this PR by adding kojo.scala with a suitable def? (I think just exporting javax.swing.JFileChooser is also an option but then we run into null ugliness so I'd prefer the copypasted def If you agree?)