New features:
- UnZip.Streams: added Set_Index & Index subprograms for inward streams from Zip archives.
- Zip.Create: added procedure Add_Empty_Folder
* Create zipada-58.0.0.toml
Moving on to Zip-Ada version 58.
* Update zipada-58.0.0.toml
Adapted an example from Alire's doc to relate Alire's `os` to zipada.gpr's `Zip_OS`.
* Update zipada-58.0.0.toml
Put [gpr-set-externals...] after headerless part.
* Update zipada-58.0.0.toml
On zip-ada's side: fixed version string.
* Update zipada-58.0.0.toml
Adapted list of executables to those actually built by zipada.gpr.
Also applied the rest of transformations described in alire#227: no top-level
[genera] table, name/version keys, [[depends-on]] array instead of table.