This also updates all usages of the deprecated Val ctor to use
either IntervalVal, TimeVal, or DoubleVal ctors. The reason for
doing away with the old constructor is that using it with TYPE_INTERVAL
isn't strictly correct since there exists a more specific subclass,
IntervalVal, with overriden ValDescribe() method that ought to be used
to print such values in a more descriptive way.
And switch Zeek's base scripts over to using it in place of
"connection_state_remove". The difference between the two is
that "connection_state_remove" is raised for all events while
"successful_connection_remove" excludes TCP connections that were never
established (just SYN packets). There can be performance benefits
to this change for some use-cases.
There's also a new event called ``connection_successful`` and a new
``connection`` record field named "successful" to help indicate this new
property of connections.
