Install multiple versions of Kicad side-by-side

At the moment it is very difficult to have multiple versions of Kicad installed at the same time on Windows. Kicad relies on environment variables and the installer overwrites the previous version.

It's common to have multiple versions of CAD and IDE suites installed so that old projects can be opened without upgrading them. For mature, tested projects that can be very important when minor changes are needed. It should be possible to do this with Kicad.