Migrate from .NET Core 3.1 to .NET 6 (#2)

And change program version to 1.2

Merge pull request #1 from Konamiman/improve-case-sensitiviness-when-…

…searching-files

In v1.0 the applications search for existing files in a case-insensitive way in Windows, and in a case-sensitive way in Linux/OSX. With this change:

* File search is now case-insensitive by default, regardless of the underlying OS.
* A -c option is added to make it case-sensitive, again, in an OS-independent way. 
  -nc also exists to restore the default behavior.

- Add the zip.sh script

- Add AssemblyInfo.cs to specify the applications version