Add some more Gpg4win version code from Kleopatra

Authored by aheinecke on Aug 4 2020, 9:54 AM.

Description

Add some more Gpg4win version code from Kleopatra

It makes sense to have that in libkleo because libkleo
is also used by the Outlook plugin of Gpg4win. This
adds support to read a signed Version file for
about data that matches the packaging.