v0.1.0

Base propagation engine, views and constraints.

Added

• ✨ Implement base propagation engine
• ✨ Offer different modes: solve, enumerate, minimize (or maximize) with intermediate assignments
• ✨ Declare derived expressions from base variables
• 🚸 Make propagators more generic using views
• 🔨 Harden clippy configuration
• 🔨 Declare common commands as just recipes
• 📄 License code under MIT