GSApp2AppImage: Bundle a GNUStep app as a standalone AppImage

The lists.gnu.org archive renamed the message's attachments, so here's direct links to download GSApp2AppImage.sh & the two helper scripts with the correct filenames:

https://twilightedge.com/downloads/GSApp2AppImage.sh

https://twilightedge.com/downloads/Make_GMines-AppImage.sh

https://twilightedge.com/downloads/Make_AddressManager-AppIm...