Adding a second endpoint for setup_panic!

[spacekookie]

Choose one: This is a 🙋 feature

Adds a second macro end-point for users to use the Metadata struct to provide their own data, overriding the defaults chosen by Cargo.

This depends on #33

Checklist

• [x] tests pass
• [x] tests and/or benchmarks are included
• [x] documentation is changed or added