Aditional layout modes

[vsolina]

Currently there's only one, fixed layout where code editor is centered and console/terminal box on the right side.

It's very common for IDEs to display console below the code editor, but mostly that's just a default layout and customization is possible.

This ticked should at least add support for choosing where console is displayed.

Optional features:

• console full screen toggle
• customizable dimensions of code editor and terminal boxes
• [maybe] an option to open full-screen console in a new browser tab (likely not a good idea since WebREPL rejects concurrent connections)