Stabilize and make ready for 0.1.0

[phdavis1027]

• Useful, low-overhead error types #3
• Rewrite serialization logic to eliminate needless copies #4
• Write comprehensive tests #5
• Check #rules syntax at compile-time #6
• Clean up code organization #8
• SAFETY comment or remove all code that could panic #9
• Clean up linter warnings #10