Enhance documentation: reference setups for developers

[ChristianMayer]

The documentation should contain as a help reference setups for developers.
The use cases should be at least:

• tester: Windows or Mac computer, no dedicated develpment tools and no intention to install them, visu runs on a external linux server or a docker image with little to none access; wants only to change files when told so by a developer ("please try to change line X in file Y to Z") and needs to report back (with instructions) browser internal data
• casual developer: Windows computer (no development tools installed yet and only wants to install something light weight), visu runs on a Linux computer or Linux docker image with some access; only wants to write a plugin or do some little code tweaks
• advanced developer: deeper development know how although probably not with ECMAScript. Runs Windows or Linux. Has already an IDE or a powerful text editor. Is prepared to do some deeper installations. Visu runs on a Linux computer or Linux docker image with the possibility to get the necessary access.
• hard core developer: System will be set up as necessary. Focus is ease of development, nothing should be quirky or feel not smooth.
  • variant a) Visu runs on a Linux computer or Linux docker image with all required access.
  • variant b) setup with local Web server