show a warning/info message when we passively change TTLs

[luto]

The PowerDNS API only supports one TTL per (rtype, name) tuple. This means that changing the TTL on one record or creating a new record can change the TTL of records that were not explicitly edited. Detect this and show a warning message afterwards reading

Because of API limitations the TTL of X other records sharing the same type and name was also changed.