Minimal Tidal-GUI

I removed some of the features like highlighting and visualization to clean up the code. It is much more readable now.

I also improved the general interface (you can now have arbitrarily many resizable editors) and implemented a first idea of user defined makros.

In future I will concentrate on stuff like this, that makes the GUI more usable and improves the coding experience.
Maybe a file/sample explorer will be next :)