I’ve never tried to do something like this before but there are ways to make something similar to what you are looking for. Most of the alternatives are based on doing this with a Linux computer and not using any IDE. So you would have to adapt it to make it work on the Galileo however this seems to be a fairly complex process because there are no tutorials for this for Galileo. If you look at “multiboot” you’ll find several websites that discuss different ways and procedures to get you started.
Take a look at https://wiki.archlinux.org/index.php/Multiboot_USB_drive they might give you some ideas on how to start.
In the Galileo you can select which image to boot from in the grub menu. The information on the grub.conf will look something similar to this:
title Linux on Intel Galileo
kernel /vmlinuz.efi console=ttyS1,115200n8
To add different OSs you’d have to edit these files with the information of the other OSs you want to be able to boot from. If you have stored other OS in your SD card or USB you have to edit this file with the correct name, image name, port, baud rate and file system you’d want it to boot.