Allow users to enable/disable coverage collection at runtime.

Provide a means for a user to turn clover coverage data collection on/off at runtime.
From the forums:

Can I clear the coverage results for a session without disabling the CC runtime engine? For example, here's a use case:
a) Start my app while integrated with the CC runtime, but keep the runtime disabled. Expect very low overhead (eg, in the instrumented code, calls to the Clover CC runtime could first check the boolean value of some env var before making the call - don't make the call if CC is currently set to false/disabled).
b) Begin manual GUI testing. Come to the starting point of where you want to start collecting CC data.
c) Programmatically enable CC engine to start collecting data (flag is now true, and CC runtime starts receiving calls).
d) Continue testing the app until the point where you no longer wish to receive CC data.
e) Programmatically disable CC engine so that no more coverage data is received (until the next time that I enable it).
I would like to use YourKit and Clover together to profile a specific use case (functional tests) out of a large collection of tests, and to have the YourKit and Clover results correlate with each other for that time period.