Improve context pattern toString
Refactor binding results to carry flags

- Use flags in binding results
- Use a binding result builder
- Carry around a 'fixed' flag
Refactor binding implementation

- Use BindRuleBuilder
- Deduplicate code
use flags in bind rules
Implement & respect fixed binding API

- Expose 'fixed' method in binding API
- Respect 'fixed' flag in rewriting
add more debugging logic to dep solver
toString and logging improvements
Simplify chains to be non-empty again
Remove unneeded 'unique' feature on CachedSatisfaction
Add Dependency type and use it for edges
Move fixedness to the dependencies, not satisfactions
Merge pull request #88 from elehack/feature/elehack-fixed-bindings

Implement fixed bindings