Remove optimizer (#82)

## Problem

To facilitate integration of the long-standing PR #55, this PR deletes
the entire optimizer module so that we can slowly add stuff back in.

Author: connortsui20

optd/src/core/mod.rs

@@ -2,4 +2,3 @@ pub mod bridge;
 pub mod cir;
 pub mod error;
 pub mod memo;
-pub mod optimizer;