This PR allows the use of Address Ranges using the CIDR notation.
To make it backward compatible, i introduced a new env variable WG_DEFAULT_ADDRESS_RANGE (defaults to the previous default of 24).
This allows the usage of smaller subnets (or possibly larger; but i didn't test that due to restrictions on my network). Client IPs will be calculated with correct IP addresses instead of making assumptions of the address space.
Philip H
Thomas Willems