[racket] disabling contracts again

Any new thoughts on adding a feature for disabling contracts?

In the past, I have been concerned about introducing contracts into 
large performance-sensitive apps, since I didn't know the performance 
impact.  I couldn't measure the performance impact without a large 
amount of work that might have to then be thrown away.  The solution was 
to simply not try using contracts.

I am newly interested in disabling contracts because my new code 
documentation tool encourages the use of contracts, as well as 
developing your modules as PLaneT packages.  However, as I am converting 
all my PLaneT packages to use contracts, I fear this will make the 
packages less useful to people who don't want the contract overhead.

Or, if no one is persuaded that this might be a good thing, perhaps 
there's a submodules angle that makes implementing disable-able 
contracts interesting to someone?  If so, it might also be relevant to 
Typed Racket.

Neil V.