New default template: as always, it must be read and approved by rejetto to be validated as the new template

- create a Tar archive now requires that items are selected
- with COMMENT button, it were not possible to replace the Default comment "uploaded by user" by an empty comment
- when renamed an item, the current name is used as default string
- the user was not informed that there was no current selection in certain action buttons
- some changes only affect the action buttons and consist of prevention messages against false manipulations
Sorry to All I committed a big blunder, downloading into a template derived from an older version, I put the correct file attachment with an evolution incorporating the invalidation of action buttons when necessary
one that has already loaded the previous version must begin again,
the new template must be reloaded