#1160 Detect file changes and ask for reload

[Pablo AB]

I save my SH3D files on a cloud syncing service like Dropbox/Nextcloud/Mega. Sometimes I edit/save a plan on host A. Then, on host B, if SH3D is already open, I have to remember that the file was modified, needing to save as with other filename and then manually merge the changes. Or risking to lost all the changes made on host A.

Therefore, would be great to detect if the current opened file was modified, warn the user, and offer to reload the file, save current unsaved changes on other filename, or even better would be to handle a merge.

[Emmanuel Puybaret]

Ticket moved from /p/sweethome3d/bugs/1202/