Improve script-calling and add sample using new func

[embiem]

I wanted to share with you my approach to call JSX functions as an alternative to the "evalScript" function.

My "callScript" function enables:

• Calling a jsx function with any arguments you like
• Ensuring correct parsing of passed arguments (escaping special characters)
• A Result & Error callback

This PR consists of:

1. The callScript function in CSInterface
2. The callScript jsx-function as entry-point in PProPanel.jsx
3. An example how to use this, using a new "Create Deep Folder-Structure" button.

With ES6 and promises, this would look even nicer. But to fit into this PProPanel example, I kept the general vanilla js style.