Cast elements passed as arguments to List mutator methods
Line numbers
Allow passing other flags to script/spec
Type casting for Set elements in mutator methods
Cast keys and values in map update operations
Refactor Type a bit

* Use casting methods `String()`, `Integer()`, `Float()`, etc.
* Simpler template method for String types
* Always return times in UTC (since Cassandra doesn't store TZ data)
Cast arguments to scoping functions of `RecordSet`