XMLSec and xz library attack

[lsh123]

The xz library backdoor demonstrated that an open source library can be compromised by a malicious actor who takes over the maintenance of the library. In order to protect XMLSec users, I have decided that I will not be adding any new maintainers to the XMLSec library unless I know them "in real life" for a significant period of time (5+ years). If / when I will not be able (or will not be interested) to continue the maintenance of the XMLSec library, the source code in this repository will become frozen / archived. Any interested party can continue updates / maintenance through forking the code into their own repository. Any distributors of the XMLSec library will decide if they trust the new maintainer(s); or if any additional security measures will be needed..