Suggestions to make getting started a bit easier

[martyall]

I've just recently discovered this project and find it extremely interesting. Just a few observations after trying to get started:

1. From what I can tell, the circ example is the primary executable target. It's currently listed as an example, which forces the user to be inside this repository to use the compiler. What do you think about either moving it to src/main.rs or under [[bin]] ? It would bring things more in line with what other devs would expect.

2. Using the test file examples/C/r1cs/add.c, when running

cargo run --features="r1cs bellman c" --example circ add.c r1cs --action setup

I see the output

Done with IR optimization
Converting to r1cs
Pre-opt R1cs size: 1
Final R1cs size: 1
Generating Parameters

However, there is no compilation artifact left behind. I guess I'm not sure what I would expect to see, but at least some kind of file describing the r1cs. I think it would be helpful if the README gave a short quickstart for compiling an example program.