'output' attribute for circuit and fuseaction

[barneyb]

Add an 'output' attribute to the circuit and fuseaction elements of circuit.xml that will control whether they emit any output. I.e. when true, behaviour is like today, but when false, the block in question should be surrounded in CFSILENT tags. Note that it should NOT behave like CFFUNCTION's 'output' attribute (which is tri-state).

In addition, the option should inherit from circuit to fuseaction like the 'access' attribute does, so a circuit can be declared one way and then individual fuseactions can supercede with the opposite setting.

Default value, of course, should be 'true'.

[scorfield]

Defer to 5.6 for reconsideration. I'm loathe to add new grammar elements now.