Implement utilities to ensure memory is zero-ed

[emostov]

Implement library with utilities for zero-ing in memory objects. The zeroize crate looks like an example of what we want to do. The goal of this libary should be to provide utilities that guarantee memory for a code object is always zero-ed, and the compiler never optimizes away the zeroing

We will want to investigate how these utilities work in the case of panics. If we can't guarantee that memory will be cleared in the case of panics that should be clearly documented.

ref: #122