cc77139ff8
Add a new configuration parameter globalTTL that all models will inherit. The default value is 0 which matches the currently functionality to never automatically unload a model. The model.ttl's default has changed to -1, which means use the global TTL value. Any model.ttl >=0 is now value with 0 meaning never unload. This allows a model to override a globalTTL > 0 and be configured to never unload. Fixes #459 Closes #512