Add nodes for curves similar to objects node like: Trasformation, selected nodes, extrude etc...

Describe the bug
The local build (run using yarn start) outputs to /gh-pages/index.html, while the live build (https://github.com/ryceg/Eigengrau-s-Essential-Establishment-Generator/tree/gh-pages) outputs to /index.html, resulting in the local build being unable to access the images.

![image](https://user-images.githubusercontent.com/36913739/99138730-da027780-2686-11eb-87fd-438b371f

Currently it looks like that:

We could use a UI theme there. I'd also rather use styleboxes and piggyback on button and similar nodes than use custom textures.

The file dialogs should get the ability to store bookmarks and maybe even to show the default folders of the OS (like Downloads, Pictures, ...)

The custom bookmarks should just be stored as a Cvar (see core/Var.h, or in-game-console command cvarlist) that is separated with ;