Add an option to enable the optimization to reduce circuit size

[elliottlawrence]

I'm upgrading from emp-tool commit 508db17 to the latest version 0.2.2. When I tested it out in our codebase I noticed about a 15% increase in network traffic.

Chatting with Xiao it sounds like this may be due to an adhoc optimization that was in the original version of the code (here). That optimization could reduce the circuit size, but could also increase the runtime.

Could we add an option to enable that optimization again?